Playgrounds require you to have children with you - for example I don't think it would be socially acceptable for a group of unaccompanied adults to show up to a playground and sip some beers while they chat amongst themselves, like you might do in a public plaza in Europe.

Municipal parks, like the kind you can find in Savannah GA, are nice third spaces. But I think there are very few such parks in suburban America that are not also mostly playgrounds. I would not count nature reserves as real third spaces.

Its usually not literally just a playground. Its usually a whole park which happens to have a playground or two. For instance, this last weekend I went to a park with some adult friends which had playgrounds, but we were there for the disc golf. There were other adults having some kind of cookout at the grills and picnic tables. There were adults playing soccer in one of the fields. Then yes, there were kids and parents at the playgrounds.

The vast majority of parks I see around me aren't just a playground. Those mostly seem pretty rare.

Most parks with playgrounds in America are, by area, 90% park and 10% playground. Or something roughly like that; the playgrounds are designated areas tucked away into some corner of the parks.

Except you're probably not allowed to drink beer there anyway, because a law against drinking in the park provides a convenient excuse to keep the park clear of homeless so everybody else can enjoy it.

> But I think there are very few such parks in suburban America that are not also mostly playgrounds.

Reality disagrees with you. Just search for parks on Google maps for SV and you will see so many where playgrounds are just a small part and the rest of the park is for everyone - https://www.google.com/maps/

My favorite ones: Las Palmas, Cuesta, Washington. And if I want to drive for ~15-20 min: Shoreline, Rancho San Antonio, Baylands.