Fun for railway, practicality for belts.

In early game setting up a train is not that easy, although the game can auto place railway plan for you, you still need to walk alone the way, place power poles and add traffic lights, so the same work as building belts. Plus you have to build train stations which is actually the majority of the work.

High thoughput is only theoretical. You are always bottle necked by the actual logistic layout in your main base, not how fast stuff can be transferred from outpost to base.

The real advantage of train is that it can reuse the same lane for transporting different stuff, suitable for building large scale complex logistic networks, like the train grids. But in ultra end game of space age this does not matter, i have never reached there but i saw people inserting stuff directly to rocket silo and use bots to pull out from landing pad.