All very well saying you can get a taxi if you want a late night, but that depends on how far out you live on it being financially viable. And it's not always even wanting a late night. If going to gigs or the theatre, they can often still end late enough for you to have to miss the end, in order to make the last train or tram home.
Apparently our last train used to be an hour later than it is now, (which would really make it easy to get home if it still was) but they made it earlier, because, according to a guard I asked once, 'it was often full of drunks kicking off' ..... the last one now is still exactly the same, just an hour earlier.