Do the airlines keep track of "revoked" passports or were cancelled (when they were reported as lost?)

That's a bit of a broadly brushed statement... Switzerland doesn't prevent you from leaving, you just need to make sure you've told the military before you do so (so that you don't get invited to do service when you're abroad). The mandatory military service only applies to resident citizens, and not to those living abroad. You're free to move as you want.

Of course if you come back you'll need to complete the same service everyone else does. However if you don't complete bootcamp by age 24 (or possibly 26?) you can't do military service, so you're automatically assigned to one of civilian service or civil defence (not quite sure what the algorithm is, but civilian service tends to be for conscientious objectors, civil defence is for those not capable of military service).

Well, that's why I said to varying extents. We don't need to discuss the pros and cons of conscription here, and of course nobody is ever completely free to do whatever they want, but you are still forced to leave the country before a certain age if you don't want to do military/civilian service. If you start and then want to quit, are you still free to come and go from Switzerland as you please?

As long as you switch to civilian service or pay the replacement taxes (both only required while you're a resident) then yes you're free to do what you want. The human rights declaration guarantees the right to leave your country, they won't and can't stop you if you want to go, but if you're resident you can't avoid the duty or tax requirements. I don't see how this is restrictive, you aren't forced to do military service, and your ability to travel is in no way restricted.

I understand that the USA has been revoking passports and refusing to issue passports to those who owe child support.

Some Gulf states seem to prevent even foreigners from leaving if they own money or could be suspected of crimes. However, these are places where employers often hold passports and it could be difficult to leave before the end of an employment contract and without taking the correct steps with the employer to cancel the visa/work permit just before leaving.

Any country with mandatory military service is likely to restrict travel for those eligible who have not yet fulfilled their obligation. Greece used to do this. I suspect that Israel and South Korea might currently have restrictions somewhat similar to but less severe than those of Singapore.

ADDED: Some religious countries (Gulf states, Ireland) have been known to prevent female citizens from travel abroad if they suspect that the purpose is to seek an abortion.

Many countries would restrict travel to someone traveling with children that might be the subject of a custody dispute or at risk of sex trafficking. For example, the USA won't issue passports to minors without the approval of both parents. Kids caught in divorces, kidnappings, molestation, and slavery might be stopped at a border (but probably not often enough).

In the past, Poland was supposedly unique among the "communist block" countries in permitting its citizens to leave easily and freely.

Uzbeks require an 'exit visa' just to go outside the ex USSR. Although this is to be abolished next year.

I can indeed confirm Saudi Arabia at least requires an 'exit visa' even for foreign workers. Even if one receives a single entry work visa, like I did, a small payment automatically converts it into a multi-entry/exit visa without doing anything else to it.

Sort of yes, and sort of no.

The US refuses to issue regular US passports to US citizens who are on file with HHS as owing child support above the stipulated amount, but last I checked we generally didn't revoke ordinary US passports issued to such persons prior to the person ending up on the HHS blacklist. It may be a different situation if such persons were seeking consular services using a US passport after getting on the HHS blacklist.

Not generally. The airline security contractors and/or the airlines may get feedback from some systems about a person not being good to board, but that's more complicated than an airline or airline security contractor keeping track of all passports "revoked" or "cancelled".

In China only persons with "sensitive" positions in the gov't are barred from receiving a passport (except when approved by their higher-ups), for (mostly) good reason. Those in the private sector aren't affected by law but there are nasty employers who (illegally) request employees to turn in their passports (or be fired). But it's not a law thing and people are free to just take another job. :)

A few years before I believed one could not exit China without a valid visa for the destination country; basically, China Immigration would take the role of docs checking. Nowadays I think it's now done by the carrier as Chinese citizens can freely exit & enter the country by e-gates without any human interaction at major airports.

Although not an outright denial to leave, visitors to Israel have to pay to leave. I've done the King Hussein Bridge crossing a few times. The irony is that you have to pay to enter Jordan and pay to leave Israel.

Oh, and regarding Russians, Russians don't need any permission to leave the country. As long as they have a visa if required, they are free to come and go. For some of the ex USSR countries, like Armenia, Kazakhstan, Belarus etc, they can even use their 'domestic passport' (their version of an EU ID card)

Cuba allows its citizens to freely obtain passports and freely leave the country for tourism or migration or whatever reason the citizen wants, if the citizen has his own means to buy a plane ticket or otherwise pay for transport. https://en.wikipedia.org/wiki/Cuban_passport

Ironically, the U.S.A. does not allow its citizens to freely travel to Cuba for tourism. https://travel.state.gov/content/tra...ages/Cuba.html

As citizen or a foreigner, you must go thru "passport control" when exiting Brasil.

Military service is mandatory for males at 18 years of age, so, you must serve 12 months, and I am sure criminal checks are also processed on everyone else when you try to leave. I think every country should have an exit control system of sorts.

This is incorrect. Typically only those with connections, or those who paid the appropriate bribes, were allowed to travel outside the country (with the exception of travel to the other Eastern European nations).

In India, there are categories of passport-holders who need clearance to be able to leave India for certain countries (mostly in the middle East). The passports may in such cases be marked "ECR" = "Emigration Check Required". Prior to 2007, that was the default, and most citizens had to first get a stamp, "ECNR" = "Emigration Check Not Required" before traveling anywhere. Usually the people covered by the emigration check are those without college degrees and not salaried or otherwise paying income taxes - in other words, mostly poorer folks seeking to move to the middle eastern countries for various blue-collar jobs. A government agency, the "Protector of Emigrants", attempted to ensure that the job offers being pursued abroad were not fraudulent or likely to leave the Indian citizen stuck abroad without the means to return, before approving the travel.

I think here in Singapore they still require exit permits for overseas trips that last more than 3 months if a male has not completed their National Service. I will check into it. Luckily I was 'too old' when I got my citizenship here :)

Thinking South Korea had some sort of restriction for males who hadn't completed their National Service at one time but if you had the money or the 'star power' you could buy your way out of it.