The ban on smoking (in every place that currently has a ban) is not for the benefit of the patrons (that is just a side benefit). Generally speaking, patrons have a choice to be in a bar or not. But the bar (pub, restaurant) is also a workplace for the servers (barmaids, bartenders, waiters) etc. where they may work 8 hours per day and more. And like everyone else today they are entitled to a smoke-free workplace (as a matter of health and of workers rights).