It’s not a tax, it’s like a rent. They built and run the ecosystem, you don’t have to be part of it if you don’t like it, it’s completely voluntary, unlike a tax.
https://www.nolo.com/legal-encyclopedia/clb-percentage-rent....
> The percent that’s applied is usually an industry standard (7% on every dollar) and isn’t subject to much negotiation.
Which is still much less than the 30% of Apple.