It's anything but dead simple. (And I went from Android to Apple back in 2020 and back to Android in 2021. It sucked, both ways.)
Yep, which is unlikely to coincide with the latest screwover from their platform of choice, giving them much less motivation to switch at that time. But you're right, the expense only prevents some people from switching.
> app passwords are the same between platforms
Until they're not. Heck, I've encountered apps that didn't support any way of transferring your progress across platforms, although the example I can think of (Clash of Clans, or maybe Clash Royale) fixed that many years ago. But there's still plenty of instances where I needed to add another login method to my account because some methods just weren't supported on the other platform.
Meanwhile if you keep using the same platform odds are you'll just be logged in because it will either be in iCloud or your Google account.
> the average user only uses about a half dozen apps
I doubt that very much. I guess maybe the average user is old people who still only use their phone for calling, texting, and maybe directions? Yeah you're right it doesn't affect them too much. Other than remembering to turn off iMessage if they switch away from Apple.
Get real.