It's not a media flatrate. It's a tax by any other name to maintain publicly funded television and radio channels while maintaining a separation of state and media (because of bad experiences with state-controlled media in the Third Reich and the German Democratic Republic).
The reason many people don't like it are:
* it feels like a third-party license fee due to how it is charged (e.g. you have to pay it yourself and it is charged per household rather than per citizen)
* prior to the simplification of the rules in 2013 many people would be subjected to "inspections" by the media companies, with ethically and legally dubious behaviour like peeking into bedroom windows and rummaging through trash cans (in the days of tv magazines)
* it costs money, unlike most private channels (via satellite or antenna)
* you have to pay even if you don't use it or don't want it
* despite being something you have to pay for, there is no obvious way to influence the programming
* although they are the only channels that are required by law to feature a certain amount of educational and cultural programming, in practice a lot of it is basically "entertainment for the elderly" (like telenovelas and cheesy romance flicks) or game shows
Personally I'm also extremely annoyed that they give free airtime to the dominant religious groups (Catholic Church of Germany, Evangelical Church of Germany and sometimes Jews or Muslims) "because culture", to the point that they always invite religious ministers or monks for ethical debates and frequently give them more weight than secular arguments (though to be fair: the religious representatives usually come off as fairly progressive although their arguments are of course still entirely based on theology).
Plus, of course, the fact that while BBC subscribers get Terry Pratchett we only get Rosamunde Pilcher -- and German actors, who are mostly horrible and take themselves too serious.
https://en.wikipedia.org/wiki/Beitragsservice_von_ARD,_ZDF_u...