Nice trip report, always fun to see how first-timers find Romania and the surrounding countries such as Moldova!

You are indeed right about the train being from the 1980s. It is constructed in East Germany (DDR) by VEB Waggonbau Ammendorf.

As for OTP Airport - I understand your feelings although it has to be put a bit into perspective. There are still lots of flight arriving around 1am (from the top of my head many of the flights from Spain, UK, a Turkish widebody) so compared to other European airports it is actually a busy arrivals bank that time. Many people are picked up by relatives, friends, so easily 70-80% percent of those waiting are just there (maybe already for a long time having come from places further away in Romania or even Northern Bulgaria) to pick up people.

That said, the taxi situation can be intimidating for those who do not speak the language and do not know how to get a legit taxi. There are taxi-ordering machines in the arrivals hall to both the immediate left and the right, where you get a receipt with a taxi number/licence plate. The normal rate is nowadays around 1.80 RON/kilometer at any time of the day and those cabs which are ordered will stick to this as they know you can get them fired if filing a complaint with the receipt in hand (to the city centre it should be no more than 40-50 RON at max, even in more busy traffic). Taking an unsolicited taxi lurking outside without a receipt or going with the touts and you get ripped off - that would even be the case for those speaking Romanian. This is why I also advice those who don't speak the language to pick up a taxi lurking outside at the old town or train station, as you get ripped off (cab drivers refusing to put on the meter, saying they don't have change, taking a detour) - and that while any ride in the (city) centre itself should never be much more than 15-20 RON (less than 5 EUR).

For 99% of all my rides to the airport and back to town I use however Uber, The service is much easier, waiting times are much less (often you can wait for hours at those taxi-ordering machines at rush hour/bad weather/busy arrivals) and mostly the drivers are customer-orientated. You are however right that they are not allowed (read: get into problems with taxi drivers) when picking up passengers directly at the terminal, which is why they only pick up drivers from the top deck of the adjacent parking garage (for international arrivals) and the bottom floor (for domestic arrivals). I am honestly quite surprised (and sorry to hear!) you had a bad experience with Uber in Bucharest as generally the service works like a charm.