But the fee that the GEZ used to collect (the Rundfunkbeitrag) does still exist and that's what a lot of people call it even the entity that collects it has a different name now, which doesn't make a difference to its effect.

I believe there are taxes in Germany that are zweckgebunden (legally bound to be used for a particular purpose), but the Soli isn't one: there were political justifications for its introduction, but it goes into the general fund and the government doesn't have to use it for those purposes.

I assume the previous poster meant that you can't tie specific taxes to specific spending buckets in Germany.

I don't speak German but the tax you linked appears a tax that is /collected/ on a certain item (sparkling wine). The GP was talking about a tax whose /revenues are spent/ on a specific thing (transit).