Yes that's one of the key services you get in exchange for 30%. Small companies really don't want to be handling sales tax requirements for every jurisdiction on the entire globe, it's a nightmare. Not to mention fraud, etc.
It's 15% for developers making less then $1m/year.
And as Apple demonstrated in Netherlands with the dating apps it is actually cheaper to use them that try to run your own payment system. Especially if you're trying to target a global audience.
