I don’t know if that should be tagged. If I start adding payment tags to everything, every single route will have so many tags and there’s already quite a few tags that I’ve already added. It’s probably going to be better to put payment attributes on the Wikidata page for Public transport in Wrocław which will be the network. I’ll think about it though.
No, that’s not how it works. MPK Wrocław, the municipally owned company has contracts with other private companies to operate selected lines. Those operators function in other cities too like Warsaw, Kraków, Katowice. In my opinion it is useful to tag them because e.g. some don’t have GPS tracking which makes it impossible to see the line’s position in real-time.