I only understood that they are kind of working there, but you dont buy a parking ticket from them, they offer you something like "looking after your car" while it stands on the parking space, and while you are away...
Back home we called this business racketeering. In Polish culture, this combinuja behaviour is considered entrepreneurship. It has precident in the '50s America with the selling of street insurance to make sure nothing bad happened to you or your property. Kind of an offer you cannot refuse. It is not so sophisticated in Poland, although try to tell a shop keeper that and you will hear a different story.
Do not pay these low-lifes who cannot even take care of themselves in their own country the slightest attention and, hopefully, they will crawl back under the rock from which they emerged. Poland does not realise what an eyesore they are and, rather than combat the social problems that have these (poor) people on the street taking money for nothing, their government would rather line its own pockets, fiddle and diddle each other. (Nothing changed since long before the days of Pan Tadeusz.)
Learn the ropes of Polish culture, friend. That's more important to you as a foreigner than the local dialect of the language.