Because they are "legal" and they are legal because the billions of dollars in taxes the government profits each year
They are legal to the public.
As long as something's legal, it's socially accepted, and I'm pretty sure that it won't take long for cannabis to become socially accepted as well. Well, some states in the USA and different countries legalize cannabis, and in my place, it's permitted to grow cannabis. It's not that hard to get cbd seeds on the internet, and I can tell you that over time, many people will have cannabis on their balconies.