What are some reason that you would make subways,buses, and streetcar be 24 hours ?

Other than working (as the other person explained), many things require you to be present early, in recreational areas there are your mountain goers, such as skiers and snowboarders and there are skydivers, so basically anything awesome needs you to be there at 6 AM, which is hard to do if you have to commute for minimum an hour and the buses aren't even running. Everyone knows that's why tourists ultimately come to a destination, not to work I can tell you that.