And whenever you tell them "please stop vaping here", unless you're a bouncer, they'll lash out saying "it's not illegal, show me which law forbids me vaping indoor; yeah smoking is forbidden indoor, but vaping is not smoking and this is just steam bro, not smoke, it's not dangerous for you".
Some venues enforce a vape ban on their own, but most don't want to piss off their customers, so many venues ignore the people who vape inside.
Vapes cause at most 1/100 the harm cigarettes do. There is no combustion products, only nicotine, and not always. The only harm they do is as a possible gateway to actual smoked tobacco. As such, banning them while allowing tobacco is completely nonsensical. It should be the other way around.