It really is. Assuming that guy isn't trying to pull a fast one (which, judging by the rest of his bill, he does not seem to be), the restaurant should 100% have covered that.
1) Waitresses shouldn't be recommending wines like that unless they personally know the diner and his purchasing practices.
2) Anyone would reasonably assume "thirty seven fifty" to be $37.50.
3) When pointed out, they should have made the mea culpa and fixed this rather than fighting it tooth and...