The fingerprint sensor is tricky, it’s not clear if it’s actually is Apple’s call or not as it’s part of secure payment flow which would make it quite problematic vis-à-vis the certification requirements that the payment card industry enforces.
FaceID devices don’t have that problem since the front camera including the FaceID IR camera simply move from the old device to the new one.
It also was technically possible to move the old Touch ID sensor just a tad harder.
Apple doesn’t lock down screens and battery replacements (currently at least) as I’ve done both on 6-7 devices for F&F in the past decade or so.
Apple has by far some of the cheapest 1st party replacement services of the major brands, and also the cheapest OEM parts now Samsung charges far more at least in the UK.
3rd party parts are also much more readily available.
I’ve just recently replaced an XS screen with a £30 kit from Amazon for a Galaxy S10 which came out about the same time IIRC the cheapest replacement screen kit on Amazon is more than £200 and Samsung does no longer offer repair services despite the fact that this device isn’t even 5 years old.
Apple does a lot of shitty stuff and whilst it’s about as far from being a right to repair champion as one can imagine in reality the long term support they offer for their devices and the fact that they release only a limited number of SKUs each year whilst moving extremely large volumes of them makes that in practice their devices are the easiest to repair whether you are using 1st party, 3rd party or doing it yourself.