You wouldn't be sitting around killing time. You'd be eating lunch or dinner at the same time, or maybe just taking a little break, getting out of the sun, having a snack, getting your baby to nap, whatever.
My wife and I went out to dinner just last week here at home and she plugged in her phone to charge as there happened to be an outlet on the wall right by our table. Nobody from the restaurant said a word.
Pretty regularly, I walk into an exam room to see a patient and find them charging their phone. I'm certainly not going to ask them not to. I'm happy to provide the service. It can't cost us more than pennies per month.