Paying to reserve park space

Public parks are starting to allow people to pay to reserve grassy areas. While this helps solve the problem of limited supply, intuitively I feel like sitting on grass should be accessible on a first-come first-serve basis. For limited amenities that can't be shared effectively and require maintenance, reservation systems seem reasonable. But, this new policy seems to be pandering to people not wanting to share.

My concern is that this will lead to public areas only being accessible to those who can pay, thus making them less public. And if taken to the logical extreme, these reservations will eventually be allocated by auction, effectively putting public spaces out of reach for those with less resources. But, even if it's first-come first-serve, those with resources still have an advantage because they can pay someone to squat until they get there.