I imagine it's because the cell providers asked for it.
The first 2 or 3 google phones I had let me turn on tethering with no problems despite it not being in my contract and somewhere around the pixel 2 it stopped working. So it seems like an intentional change on their part, and likely one that Apple also enforces. To change the flags mentioned previously you also need root, so it provides quite a speed bump for folks trying to use tethering despite it not being in their contracts.
Not sure if you realize this but google doesn’t build android for you, it builds it for the carriers so what is in your best interest is not really considered. You aren’t the client.
I don’t think it’s quite that simple. Google builds Androids for users, but the primary retail space is owned by the carriers. There are occasionally a few lines the carrier could tell manufactures (including anyone selling android) not to cross or they won’t sell that phone.
Phone manufacturers alter from there per carrier demands. Phone manufacturers us Android because it's free.
It's brilliant on Google's end.
Perfect example, is WiFi calling. That was available on Android forever, but only T-Mobile didn't restrict it. ATT and Verizon had it disabled because of how profits are calculated on cell sites. There's a whole per minute, text, and data calculation that shows money flow. T-Mobile allowed WiFi calling way back when because the network was a dwarf to the big carriers. And then apple caught up like normal and acted like they invented it, but don't even get me started on apple.
