Q:

Why do conductors hold on to your ticket for the duration of the ride in ex-eastern block countries?

I'm doing a bunch of long distance train journeys in Eastern Europe, just like on the transibirian railway, after the conductor showed you your compartment, he keeps your ticket until just before your destination when it is returned to you. Why do they do that?
I noticed people paying the conductor directly without getting a ticket, so he would keep the whole fare to himself, could this be related?

A:

in Russia, if you buy railway tickets via internet and next print it on terminal, you receive another version of a ticket, and conductor cuts off only small part from your ticket, where was wrote duplicated information about your destination.
As answered above, it is for control to get off exact on your station, and wake up sleeping passengers for half a hour to arrival.
If you buy ticket on station, you get old version ticket without cutable parts. So conductor keeps it all before destination.

A:

I'm pretty sure that in modern times, this is for the train conductor to keep track of who's going where, both to make sure that people don't overstay on the train and to wake the passenger up before their station.
But, being familiar with Soviet realities, I wouldn't be surprised if in Soviet times MastaBaba's answer was at least part of the story as well - i.e. to prevent people from getting off too early. (I'm not saying this is certainly the case, but it's a plausible theory). Keep in mind that some major train routes passed right by "closed" towns (e.g. one passes right next to the Baikonur spaceport in Kazakhstan). Also, a used train ticket (in both the old Soviet system and even in Russia today) is a much more serious/official document than a used train ticket or used boarding pass in Western countries. It is recognized by police, for example, to determine registration requirements (where you must register in any new place within X days of arrival) - so it's not just a matter of checking the ticket at the disembarkation station (which actually almost never happens), but a matter of not having proof of travel and proof of arrival date later on.
Actually, when I did the TransSib in summer of 2012 (on lots of local trains for chunks of the journey rather than one continuous trip), I haven't seen tickets being taken away for the entire journey in Russia anymore, but I did see this on some sleeper trains in China (conductor takes your ticket and gives you a temporary replacement card).

A:

Those who say it is a leftover from Soviet times are correct. But the reasoning was far more prosaic than the totalitarian restrictions on traveling: financial accountancy.
Conductors would happily let you ride for a bribe (which amounted to a fraction of the official fare). To fight that, there were inspections. An inspection would board a wagon, count the (possibly sleeping) passengers and then have the conductor present the tickets. If there were less tickets than passengers, the conductor would be reprimanded.

