Assuming you're American you may be missing just how strong the USD is and how expensive $37 is for much of Europe. -You- consider it cheap and that's the whole point of the price rise.

Compared to the price of a round-trip plane ticket to Paris, hotel, and food for the whole trip, this ticket increase is immaterial for anyone who's already well-off enough to be a tourist. And the whole point of the article is that the price increase is only for non-EU citizens.