Trying to maintain a single deployable Windows 10 image for these devices was a real pain and it often was the touchscreen drivers that gave issues. Drivers with the same device/driver IDs but different settings if I remember correctly (it's been awhile since I was involved in this stuff). Touchscreen orientation and calibration was also a nuisance between models, which is where I suspect some of the driver customizations done by the OEMs are needed.
I think the market forces are just getting something as cheap as possible to market that satisfies the bare minimum. It's assumed that you won't be fresh installing anything onto them. I found a lot of hardware in this class was okay as a single-purpose device where you'd only ever be running one application at a time (though barely so if what you're running is a web browser).