If people are 21 or older and in a bar, they should be responsible for themselves, Imo. Obviously bars should not serve people who are quite apparently intoxicated already, or overserve, but I cannot see making bar owners responsible for making sure a customer they ask to leave gets home safely, as long as they are not driving. If they put them into cabs, who pays? There has to be some level of personal responsibility, Imo. Should they call the police and let them deal with it? Police are not taxi services either.
I am not speaking of Shane's situation specifically. But I would guess that bars ask people to leave all the time and I can't see how they could run their businesses if they are required to oversee each one to their doorsteps. But jmo. Not sure what the answer is, except maybe round up the people Shane came in with, in this case, and have them leave together. Safety in numbers, supposedly.