Well, it's part of your gross salary, so you end up paying it yourself indirectly.

Not to mention it's also cumbersome and bureaucratic. Though subsidizing public transport is a good idea, I wasn't a big fan of this implementation when I worked in France. It would be much more efficient to just subsidize local transport tickets directly, or just make it free of charge and save even more unnecessary costs in handling tickets, hiring ticket inspectors, etc.