(Also I have 666 reputation right now, please don't ruin it)
I used to work at FAANG there, one of the managers was a fun guy. For a month he committed to do the same thing as the people who collect cans - every 04:00am he went around town, collecting bottles and cans. Turns out you can easily make 100-200eur a day with this. But it's a highly competitive business.
There even was/is a bit of a campaign to promote that, e.g. with slogans on bottle labels. Some places also have started putting up small "bottle racks" with trash cans.
I've lived in Germany, and this was one of the things I quickly adopted after seeing the locals doing it. An interesting anecdote is that can/bottle collectors always approached me asking if I'm finished with my drink (I had a drink outside almost daily), but I never felt threatened or anything. They were generally super polite, I'd usually reply with "I'll leave it here" and they went along their way. Very different experience than anywhere else!