This has been going on for a long time, really...
Starbucks offers free wifi with drink purchases, but didn't they make it time limited in the process of the switch to AT&T hotspots? I think a number of other chains also have tried time limited access -- there's a tea place I go to in Chicago and they give you a code for 2 hours or something on your receipt. There was an independent in my neighborhood there that also turned its wifi off on the weekends. They've gone back and forth over allowing plug-point access, too.
At the extreme end, there's a coffee shop down the street from me that has an open porch on the front with seating and outdoor power points. I not infrequently see people sitting there when the coffee shop isn't even open to use the wifi and power outlets. In a loosely related rant, at the library here, there are
so many people who bring their laptops in and watch online video (I guess because there's free internet and it's air conditioned) that there aren't free tables to use if you actually want to use them to read the
books. And twice I brought my notebook there just to log into their network for five minutes to print something out, and there were so many people camped out there that the router wouldn't assign me an IP...
Consumers have to be reasonable too -- free wifi isn't an invitation to turn a coffee shop into your home office.
When I'm doing things like writing stories, I like to drag my notebook to a coffee shop and people watch and write. I write better in public spaces like that. But I do it in 2 hour chunks or less -- It's obnoxious to camp out there for eight hours with your notebook and your business files and use two chargers for your phone and notebook and conduct your job from there all day.
I think one of the challenges is that, once you get into things like time-limited access, unless you do it by manually asking people to leave, the kind of system that Starbucks has AT&T run is too complicated to expect some poor independent coffee shop person to set up and run.