Because trains cost money? Everything can't be free or cost less just because you wish it so.
I'm a big proponent of no-fare subway's, but I don't think the MTA should just do that without a revenue source to replace rider fares. It would result in a completely broken subway system.
Huh? Free? A ton of tax money goes to both road maintenance and public transportation. This kind of price hiking comes off as a double-dip. Surely they have enough money in the budget already?
> but doesn't common sense suggest fewer riders mean they don't need as much money?
Not necessarily. Consider: what would they cut? Run fewer trains? Reducing frequency has a huge negative effect on how convenient transfers are, which means you're likely pushing more riders away. (It can be the difference between hopping off one train and catching a new one 5 minutes later rather than 10 or 15 minutes later. Not a fun change in the middle of your trips!)
That can then lead to even less fare revenue... and you really don't want that, it's the infamous transit death spiral.