This can only happen when EVs are rare. If EVs are a significant percentage of all cars, there will no longer be free charging. 100 EVs wanting to charge at 4 chargers at a movie theater won't work.

Yep, this is absolutely true. It's just an added benefit that will probably go away someday. Though even in places with lots and lots of EVs there still seems to be free charging available occasionally. For example, one of my kids has free charging at the parking lot of their workplace. And I've seen photos of the Google and Apple parking lots in CA with rows and rows of free chargers.

Who paid for the electricity? The government or business?

I don't know, but it isn't particularly relevant because it is so minimal as to be negligible. Commercial electricity is around 7 cents a kWh in many places. So when I go to the supermarket for 40 minutes and charge 4 kWh, it's like a 28 cent "coupon" to induce me to shop there instead of at the supermarket across the street that doesn't have chargers. In most places, the local business pays for the electricity.