Maybe I'm not understanding. I have JS(I said DH in a previous post in Biden speak) and had to pay a tax even though the ticket price was $0. That was less than a NR tax or much less than than ZED or Buddy pass.

Thus, a flat tax portion and then an additional added tax based on the CC charged "ticket" price.

IOW The .gov is involved(worldwide) so intentionally nebulous as you alluded to.