This is just my opinion, but a 30% tax is there because they provide something that the competition doesn't. And that is automated security updates by default for at least 5 years and user friendly app permission management where I really can trust my settings to provide me privacy by default.
You will not get that from Google, they barely support their own devices for more than 3 years, I still have no idea if advertisers are allowed to read my gmail or not.
I remember recently a friend getting an old ipad mini with a nice screen but poor cpu specs, 1gb ram. And guess what, it ran fine, it's getting security and feature updates the same day as every other apple device. TouchID worked, everything actually just worked I can trust that thing my bank account.
And recently I found my old Nexus 7 with amazing specs, quad core , 4gb ram, 1920:1200 screen and now I have to do bootloader & operating system surgery just to get the thing to work.
Everytime I've heard of someone get their bank account hacked it usually has started with a text sent to an out of date android phone. For that reason alone I can't recommend a non-technical person to use android unless they understand security or it's on a brand new Pixel device.
If I'm building and deploying software and I want to have the piece of mind that all my users are running it on a secure platform that at least tries to respect their privacy my best choice is an iOS device and for that Apple wants a 3rd of my revenue.