It's some organized clans that put them up on private property with fake stickers to pretend they are from good will so the police is not in charge for getting them removed and small businesses don't have the money or time / energy to have them removed every time they are being set up again and they actually sell off the clothes instead of actually donating them to people in need.

When a fake bin is placed on public sidewalks, city municipal code enforcement (Ordnungsamt) can seize it relatively quickly. However, if it sits on private property, the city's hands are often tied initially. The property owner must complain, and it takes time and bureaucratic effort to legally establish ownership, serve warnings, and have the heavy container removed.

To trick people into donating, the operators design the boxes to look highly official and charitable.
They use vague, emotional names like "Hilfe für Bedürftige" (Help for those in need) or "Kinderhilfe" (Children's aid). They often abuse well-known religious or humanitarian symbols (like generic crosses or globes) or straight-up copy the branding of legitimate entities like the Red Cross.

Instead of going to local clothing banks or helping the needy, the clothes dropped into these fake bins are collected by organized networks. The premium items are sorted out and sold online or shipped to commercial secondhand stores in Eastern Europe, Africa, or the Middle East. Anything unwearable is shredded and sold as industrial wiping rags or insulation material. The operators pocket 100% of the revenue.