Every Sunday - mostly - in front of Hobby Lobby, which is closed on Sundays - a bunch of car enthusiasts have a little show. It's a lot of people.
I'm sure they have "permission". Saturdays, in the lot of BAE - there is often but not always, a farmer's market. I am also sure - they have permission.
If you go down to Lancaster Park - TODAY - I'm betting you will see huge crowds of people celebrating and having picnics and games and so on.
I am betting they do NOT have any kind of permission - but they're also not hurting anyone. It's a public park.
I suspect "illegal takeovers" like this happen A LOT all over the country, but as long as they're not hurting anyone, people just let it go. I mean, let's for the sake of argument say there are pizza places and liquor stores in the plaza - you might actually WELCOME a party crowd in your parking lot, even if you didn't give your permission.