Right, so at that point in time I can take my contraband out of my checked luggage, and into my hand luggage? And refuse to open my hand luggage claiming it was already checked?

No, as you say yourself... this is very much a theory, not the practice.

If your carry-on has been checked, you'll be able to show the second customs officer the declaration of said goods and the proof of payment of any due duties.

Without those papers, you'll need to pay all due duties, whether the goods are in your carry-on or your checked bags.

The theory aspect applies solely to the point, that customs are allowed to check your carry-on, as it will never happen that they do active checks. What remains is however the passenger's obligation to declare any goods when he crosses into Schengen. The two signs (green/red) after immigration aren't just there for decoration. In other words: If you pass the point during transfer without declaring and they stop you, you'll have to pay the duties and on top of that fines. You might even get your stuff confiscated.

BTW: It's the passenger's duty to declare. If he has something in his carry-on, he will need to declare it before joining the Schengen area.

It's frankly surprising that you still continue to hang on to your opinion even though the rules on the matter are clear and apply to the whole Schengen area. Whether you find these rules logical or/and practical is irrelevant to the discussion. I therefore suggest that we stop this whole OT now.

On the page referencing the rules, there is a note that there are instances where they can still in some cases examine anything.

Even within the EU, there are restriction on quantities that can be brought without paying taxes between member states on goods such as alcohol and tobacco. So you can't even for example, enter EU in Warsaw, buy a ton of cigarettes, then connect on to Germany and refuse to allow your hand luggage be inspected.

Doesn't even have to be at a border where a baggage check takes place. It's not uncommon in Germany to see customs in the A2 motorway well away from the border. I've been fortunate enough to be subject to a random check at the central station in Stuttgart. Customs from Belgium and Germany can often be seen near Dutch border, etc.

You keep on claiming that those signs exists after immigration, while in fact, I have never seen them in CDG despite connecting there to other EU countries at least 10 times in the last few years.

The practicality of those rules is much more relevant to this thread than the theory.

I can't speak for CDG, but they do exist at other major airports including FRA and AMS. They don't exist at LHR, as LHR is not part of the Schengen area. I know that they don't exist at smaller airports, where passengers arriving from non-Schengen origins enter baggage claim immediately after immigration and pass customs as passengers arriving at their final destination.

BTW: I don't make claims. I state the rules and linked the source explaining them. If that's not to your liking, get hold of some responsible from the EU and make them change the rules.

For now this won't change anything: The rules exist and are passively enforced (i.e. not officers actively checking you).This however doesn't change the fact, that the passenger has to step forward and declare goods if necessary.

I don't disagree with that, but that doesn't change the the fact that PAX arriving at some of the biggest Schengen airports have no way of knowing that they should do that...

Just a little side note

The whole customs issue at hand here is EU related, not Schengen.

Norway and Switzerland are Schengen but not EU, so you could transit ZRH and at destination hand luggage and checked baggage are liable to be checked.

UK is (currently) EU but not Schengen. So even if there is no passport control if you are solely connecting at LHR, declarations to HMRC are still required and, in theory, they could, should, and probably do sometimes do checks.

Yes indeed. I wrote Schengen to exclude the situation regarding the UK, which is somewhat specific. They don't really care regarding transit passengers and the control once you actually enter Schengen will usually do the trick.

While it is correct that it is the pax's obligation to declare, this has nothing at all to do with Schengen or not. Schengen is a travel area and not a customs area. When travelling from Switzerland to Germany, you need to clear customs, but no immigration. When travelling from the UK to Germany, you need to clear immigration, but no customs.

Being in the customs area of an airport, all of you baggage including yourself can be inspected in most jurisdictions....

Couldn't agree more. Was at TXL a couple of days ago. Landed remote gate. Once bus arrived at terminal, mass of people just walked thru both green and red channels. Everyone who walked thru red channel just strolled thru as if it had no meaning whatsoever.