It's not easy being a teenager. There are only so many places you can go, and most require buying something. When I was a teen, I spent a lot of time at the bookstore and the movie theater because those were some of the only places in the town square where you could hang out for long periods. I went to the mall, but by the time I was 13, malls across the country began closing, and the ones that remained open were often hostile toward teenage customers. My friends and I would sometimes even drive to local playgrounds at night because those were some of the only places we knew we could futz around without any adult interference.
Long story short, there aren't a lot of places where teens can just hang out. This reality is well demonstrated by an anecdote a woman recently shared on Twitter about a teenager getting kicked out of a coffee shop for reading without buying anything.