If Panera Bread doesn't do anything about it, it's going to be their loss. I don't interpret free Wi-Fi to mean an invitation to run my office from there or any other place that offers it - just because the condiments and creamers at WaWa are free doesn't give you carte blanche to swipe them all.
I do think that's a universal concept - when someone leaves free donuts at the office, you don't take the whole box to your desk.
I'm also of the opinion that in general, when you eat at a restaurant where there's a server waiting on you, and you've paid your bill, it's generally considerate to leave fairly soon afterward, especially if the establishment is fairly busy - the servers are assigned stations, and when you continue to occupy it without paying anything more, you are taking away from the server's livelihood. I've had members of my family frequently comment that they hate this - customers lingering in a crowded restaurant after they've paid up. They might get four or five stations, and two of them are occupied by clods who won't leave.
I realize that you can't force people to be considerate; that's what freedom is supposed to be - you're supposed to be free to not have to behave the way others want you to. I do think management has every right however, to say, look, your continued loitering is now cutting into my profits. Either buy something, or move along. Bars and clubs with performers do this all the time - buy drinks or leave, the show ain't free.
It is a little rude to set up shop in an eating establishment, but as long as management allows it, the people who are hurt the most by it are obviously not concerned about it.
