If the subway costs $1 and 50% of the jump the turn-style 50% of the time the cost to ride the subway in aggregate is $0.75

Sure, if you take some asinine ideological hard line about the goodness or badness of taxation you'll probably get your panties in a knot but if you look at it from the perspective of who's spending money in the economy a little bit of broadly applied fraud and a little bit of tax reduction are the same thing because they shuffle money around in the same manner.