Exactly, plus scale. You have to sell a boatload more $350 devices to make the same profit as much fewer $750-1000 devices (or even $600 range)
Apple simply doesnt want to cater to the low end market; there isnt huge profits there per customer. The SE is the best compromise I think you will see.
Most of these $300-400 phones if you break them you are SOL; no support, no stores, notta nothing. You are on your own for that price as that support costs $$ and thus profits.
Thats why these Chinese companies can sell $300-500 phones all day and make money. Plus you get 1 maybe 2 OS updates; no development cost.
Here's the other value proposition issue. You can buy a $700 iphone 11 (or 12 which will be OLED and 5G and somewhere around that price) but getting 5 years of updates/support. So that is costing you $140/year. That is less per year cost than most of these $350-500 phones that will get 1-2 years. This one gets you 3, sure, but will the hardware last you 3 considering the low end processor and no 5G which you will want in a few years (the 5G 4A is rumored to be $150 more which isnt that great a deal then)