The comment was about heroin. Were you offered heroin?

Is cocaine and marijuana available from the government too? If not, what relevance is your comment?

Was this the first and only time you were waiting at a bus stop in Switzerland? If so, perhaps a notable story, if not then we'll need more information to conclude how bad this thug problem really is in Switzerland.

Sounds like you have easy options for some common drugs. Not a bad thing perse and sounds like they didn't offer any opioids

"waiting at a bus stop in Langstrasse" -> what were you expecting?

If you think cocaine and marijuana are comparable/interchangeable with heroin, you might want to educate yourself on the topic a bit more before trying to make a quip.

Is it too long, too little or what? Red light districts, official or not are the place to get drugs in european towns. Langstrasse is basically an official place for that, at least the most official Zurich has.