Our solution is to have separate checks including drinks and tip upfront. Don't like that....then don't come. Be sure the restaurant offers separate checks, puts separate drinks on that tab, and includes the tip on their tab.
I make a habit of showing up first. That way, I can tell the server that no matter what anyone else says, make seperate checks. In fact I'll tell the server not to try and figure out by couple or family, just do seperate checks! This way, if there is a brother or sister who are generally taken advantage of, when the scammer arrives and tells the server to put them together, they can say it's already been done seperately.
When the group is all arriving together and I can't be first in, I still make it a point to grab the hostess or someone on the way to the table and instruct them that the table needs to be seperate checks on matter what anyone says. I tell them not to even ask!
What a shame that this is neccessary!
Regarding the idea that some are of humble means, I find that those that are truly without and are unassuming will simply not go out and put themselves in an embarrasing position. Those are the ones I do my best to try to invite for hospitality, and I make sure I let them know that I do not expect reciprocity. If they insist, fine, make some cookies.