I love to hang out in coffee shops. This was the case even before I would bring my tech. This appears to be true of many. It seems to me that reading and writing are solitary tasks but we like to engage in these behaviors in public. Perhaps this is a way of offsetting the mental isolation.
I am guessing the establishments have a love/hate thing going on with us. Even at coffee house prices for a latte we take up space and expect good wifi.
I like Panera’s policy. This seems reasonable.
Looking around, I would say that I am not taking up the space required by a potential customer.