It is neither compulsory (to watch TV) nor is it added to the cost of anything, it is a stand alone charge levied against a service which they have no investment or authority over, so by definition if is not a tax.
I understand what it was 40 years ago, but now it is obsolete and just a cash cow.
If people want to pay for the BBC and it stands on its own two feet, great. But it is acting like a monopoly in a competitive market and the only thing keeping it afloat is outdated laws.
Just my opinion, which is why I don't have a license.