The only companies bitching are the ones who want a complete free ride on Apple's platform, where Apple gets ZERO. While 30% (and 15% for subsequent years) might be high, I use Patreon which takes 10% of pledges for payment processing and hosting. What Epic and Spotify want would be the equivalent of Patreon being forced to host my content for free, and letting me use my own payment system in place of theirs, on THEIR platform, with them getting zero.
When Spotify start paying reasonable royalties, then perhaps I’ll care what they say. As for Epic, They made their bed by breaking the rules. Generally 7nder US law that means the do not have ‘clean hands’ and in our system, “equity only comes with clean hands’.”