We're not talking about a global scale. We're talking about a US-based survey about US-based people.
> Apple doesn't make a product that costs less than $430 (the SE). > $400 is a lot of money
Except every two years you can switch carriers and pay $0 out of pocket. Heck, if switch today you get a base iPhone 12 or iPhone 13 they don't even raise your contract vs BYOD. And if you want to pay for a more advanced iPhone (say, upgrade to the Max Pro for an additional $400), they finance that over 2 years.
> In lots of families it's iphone for the grownups, android for the kids.
That argues against what you're saying. Unless you think that kids as independent economic actors need to be accounted for separately than their parents, in a lot of families the people using Androids are children of parents rich enough to afford iPhones.