While these things feel like taxes they are not because they are not managed by the government. Taxes (no matter their labelled purpose) are pooled and spent according to the yearly budget. Other fees collected by an agency are spent just for that purpose maybe propped up by money from the tax pool. Besides budgetary reasons, having a separate TV fee prevents (in theory) the government from interfering with the public media as there is no direct dependency.

Sounds like the options list when you buy a new BMW. Now I know where they got their inspiration from.

The fee not being a tax in Germany is an important distinction for a very basic reason: The government has no direct control over it. The whole reason for the public TV and radio to exist is to create independent media, especially also independent from the state. So while the government is involved as far as it guarantees the system, it has no further control about it. So the government can't threaten to cut funds, just because they don't like critical reporting. And guess what, the right wing extremists are constantly asking for the end of that system.

I’ve also seen this done on fines; it seems the fine is set by legal statute but, (and it’s just an impression), they get around this here in California by tacking on court fees, etc..