It shouldn't be too expensive for a restaurant to do.

Although a restaurant can get by without wifi, most modern restaurants have it for managing OpenTable, monitoring yelp reviews, ordering supplies online, etc.

I guess the signal might get a bit worse the farther away you get from the wifi router, but in general, providing wifi to customers shouldn't cost any additional money.

I think the real cost isn't that they use wifi, but that they actually sit around longer but purchase less in their time spent at the establishment. It's really important for restaurants to turn tables over quickly.

People usually don't lurk in those places anyway, I think. Usually there are coffee shops etc. that are much more open to that kind of thing.

"It shouldn't be too expensive for a restaurant to do."

Heck, most McDonalds restaurants have free wifi these days, and that's about as cheap as it comes.