Correct, consider the typical traction current is in the order of 1kA, and then think of a station made from steel structure with a ground connection at the one end, and it is 100m long so a train can stop there with all cars under cover. With 1R resistance on the tracks in the station there is a 1kV drop along the length of the station. Think if the structure was only bonded at the far end, and you were to incidentally touch the rail or the stopped train while simultaneously you were holding on to the steel structure. Even if there was 0R1 resistance the voltage would still be over 100V. Thus a lot of bonding conductors, all of which have to be capable of handling the full traction current of the line.
Even with rail cars which are around 12 tons empty, and a traction unit of around 40 tons a train is still capable of pretty good acceleration, limited only by slip of the tyres on the rail. That does need some serious power from the overhead line and this travels through the rails.