In theory the vapour might have as strong a smell as cigarette smoke; in practice even the most strong smelling vapours are mostly comparable to the smell of personal fragrances, and we are ways off from banning those as well.
To me, it seems like many people have this weird "ick" about natural biological functions. Some are understandable - like body waste, and sneezing/coughing that could spread contagions. Regular smoking I can understand from the standpoint that it smells bad.
But vape clouds typically smell good. But they are visible. So people are reminded of "ick - breath!" meaning something similar to coughing/sneezing (and not covering your mouth/nose)...
Yet, nobody seems to have an aversion to everyone around them just "breathing" normally - or even an exasperated sigh or huff - which is arguably just as much breath coming out as someone vaping.
Just that it is invisible - and now no "ick factor" if you will.
It's kinda crazy; here is something that can and could really help smokers, yet being vilified because of some weird hangup people have with breathing - because it is visible. It is similar to how some people love to eat chicken nuggets, but give them a bone-in chicken wing and all of a sudden it is "gross - it has bones" - like the nugget is somehow more sanitary or further removed from the chicken because it is boneless?
/humans are weird
If it's rude to spray perfume or eat smelly food, then it's also rude to vape.