Railways selling more tickets than train capacity cannot be called corruption - it is a trade-off: Tickets will be available, but if one is not comfortable travelling in crowded trains by all means, he/she can wait for another train with the added disadvantage of perhaps having to wait more than a day (especially for outstation trains). If railway dept. stops selling tickets quoting capacity they will be pulled up by the general populace - it will lead to a riotous situation.

Ok, you may say that because of this railways is getting a lot of money (very true) and that they are not improving services commensurate with that (quite plausible). But consider this: How many bogeys can a train have, and how many trains can be run on the same stretch of track? It all boils down to logistics and safety given the sheer number of people travelling. It is a sad truth that India's population growth far exceeds the pace at with its infrastructure grows - now we cannot put the entire blame on slow growth of infrastructure: It may be growing fast already and reached a point where any faster may not be possible.