It's a heavy tax to protect the ignorant. I hear things like this and think how I've been using a computer for nearly 4 decades and it's never once happened to me. Maybe those types of people need to re-evaluate their technology choices (maybe iPad is more appropriate) instead of taxing the entire ecosystem to protect them from themselves.
If you count the number of ignorant people who use Windows versus the people like you, you'll quickly realize the tax is very cheap for the level of protection it offers to the number of people it offers it to.
A popup warning is not a heavy tax.
low income countries don't have the money for iPads. My parents run on a 300 Euro computer bought 5 years ago. My dad is technical enough to get around a computer, but he's in his 60s now. My mom can open Facebook and youtube. Sometimes either of them downloads stuff, and opens them. So your solution is "make millions consumers spend $$ on overpriced hardware and even more closed off system, so few hundred open source devs don't spend 500$ to verify their app (which they will have to do if they want to release on the iOS platform either way)" Ain't no way.