I don't think that's really what we've lost. Blockbuster was a third space not because of its staff, but because it was a place you could say "meet me here" and hang out looking at movies with no (or very little) expected monetary output. Same as arcades in the mall, or cheap matinee movies. A better framing might be where would a teenager, today, say "meet me here" to their friends. I think you'll find there's many fewer around you today than there was 20 years ago.

That doesn’t match my experience if your bar is really as low as “won’t throw you out for not buying anything”.

Obvious anecdata, but within an easy walk or bike radius of me (a couple miles) there are 3 public libraries, something like half a square mile of parks, a few public basketball courts, a few public tennis courts, a public baseball field, a bar over the baseball field that welcomes children (it’s one of the veterans things and has board games and what not), at least a dozen other businesses that don’t care if you buy anything, and your usual litany of Walmart kind of places that can’t be bothered to track who is buying and who isn’t.

I don’t have any issues finding places to hang out for free, and I use them, but they’re pretty sparsely used so it’s not as 3rd space as it used to be.

Eg I walk my dogs most mornings, and I rarely see more than 1 other person at the park or dog park at 7 or 8am.

It feels to me like 3rd spaces are disappearing because people don’t use them, rather than people don’t use them because they don’t exist.

Definitely, and renting a video itself was often a communal activity. You'd be hanging out with your friends or family and get the hankering to see a movie, so you all pile in the car together and see what they had. You'd argue back and forth about this movie or that movie, and you had to be flexible since your first pick might not be in stock. Strangers would give you suggestions or you'd see what was recommended by the staff. Lots of times you'd end up taking up something completely different than what you had planned.

We are unfair to teenagers today; give them no place to go and then we feign surprise when they act up. According to Harper's, there's a 20% decline in kids playing baseball--their noses are in their iPads. You can't take children to the mall because malls are dying. Too many parks are places where bad things happen. I don't know what the solution is.

Malls still exist. As do public libraries, community rec centers, gyms, and pools.