As long as this system is a fixed price and is independent of the salary you earn, its benefits the rich more.

Its the same principle with kindergarden and late fee; Without a late fee, people sometimes were late getting their kids, with late fees more people were late getting their kids. Now they were able to 'pay' for this.

You now can pay for having less traffic for you. Who can afford this? The rich/richer person.

This increases inequality.