Update, 3:50 p.m.: Well, that was quick. Curbed reports that San Francisco has already suspended its ill-advised grass-reservation program amid public outcry. In a statement issued to Curbed, the San Francisco Recreation and Park Department writes:

Given the confusion of our existing policy we want to make sure the public understands the purpose and intent of our reservation policies to protect and maintain our open spaces that is balanced and honors our commitment to accessible, usable and equitable open space for everyone.

We will continue to be creative in balancing all these issues, and we will do so ensuring Dolores Park is joyous and safe for all.

Original post: Please don’t step on the grass—without a reservation.

In a move that can only be interpreted as a fifth-column scheme to incite class warfare in San Francisco’s desirable Mission neighborhood, the city’s Recreation and Parks Department will start renting small sections of Dolores Park to picnickers who reserve online, including corporate groups.

During the two-month trial period, wannabe al fresco diners can claim a section of turf via the department’s website. The fees aren’t prohibitive: At $33 for a group of up to 50 people, it might land at around a dollar a person. There is, though, a $200 security deposit. At a time when half of Americans can’t pay a surprise $400 bill, that’s an awfully steep price to sit in the park.

Groups without a table, or with fewer than 25 people, don’t need to rent the grass. The poor, the unbanked, and the spontaneous are welcome to picnic in beta mode. And most of the grass remains a free-for-all; only three sections are available for reservations. But, the application cautions, “the park can be very congested and space is not guaranteed and you can not locate in an area that is reserved for another group.” (Italics mine.)

I don’t think the City of San Francisco has really thought this through. On a practical level, requiring a security deposit, an online (or phone) reservation, and a fee is bound to wind up excluding the less well-to-do as well as longtime Mission residents, many of whom are Latino. The likely outcome is that longtime parkgoers show up to find that swaths of Dolores Park have been apportioned for company events, birthday parties, and the like. As SFist notes, it sets up the park as a site of confrontation between locals claiming park space by tradition and newcomers claiming it by pointing to receipts on their smartphones. This drama was previously enacted on a Mission soccer field in 2014, when tech workers who had paid to reserve the pitch tried to displace local teenagers.

Pay-to-picnic would be a bad idea anywhere, but it’s a particularly terrible one in San Francisco, where activists have worked hard to assuage the pains of the city’s housing crisis by encouraging new construction of all kinds. The decision to rent out a public park on the internet fulfills old-time San Franciscans’ worst fears about newcomers and the changing city, and fuels the fearmongering that produces counterproductive initiatives like the Mission construction moratorium, a ballot referendum that failed last year.

This isn’t just a San Francisco problem: All around the country, fees and reservations have been creeping into park spaces like playing fields, tennis courts, and grill areas. (Dolores Park already rents tables for children’s birthday parties.) Putting aside, for a second, which populations are liable to benefit from these restrictions, they represent a philosophical challenge to the American idea of a city park. It’s not just that city parks should be free, though that has long been the tradition in this country. Public parks were some of the first places where social classes met and mixed.

The fundamental idea under assault here is that parks should be open to the whims of passers-by—invitations for detours, naps, contemplation, mischief, and romance. Urban life is chaotic; so are parks. The problem isn’t that the allocation of park space isn’t equitable or progressive. It’s that anyone feels it needs to be allocated at all.