Check reviews and ratings of any third-party store before you get your phone repaired. There are great ones and there are terrible ones, just like with any service business. And if anyone from any store tells you they buy iPhone screens from Apple, or that they do use "genuine OEM parts", now you know--they are lying.
If you get your home button repaired by a third party, now, Touch ID simply won't work. Seems reasonable considering home button issues that would require repair are relatively rare--phones with destroyed home buttons are usually in such bad shape that the owner is just glad to get a working phone back, never mind the Touch ID.
Apple Stores usually won't work on phones with bent frames, severe water damage, etc. anyway--they'll just try to sell you a new (refurbished) phone. Third party repair stores will attempt the repair and can often fix the phone, resulting in a happy customer who gets a cheaper repair and gets to keep the data on their phone.
There actually are AASPs for the iPhone; however the only ones that exist are fairly long-standing and grandfathered in. Apple does not allow for new AASPs. I have a very close friend that works for the lone AASP in Auburn, AL (notable because Tim Cook is an Auburn aluminus).
They can do the repair, but it's not a painless one because it does still require a good bit of back and forth with Apple.
haha no, they either use completely fake screen/glass, or fancier "higher quality" (as in not completely shit) recycled gorilla glass + counterfeit screen combo.
What is worse there are no 100% reliable sources of spare parts and you can never be confident about the next shipment.
We have gotten to the point with our distributors where we order in such large quantities that they know us personally--and they also know we're going to send a screen back if it even has one dead pixel. So they send us their best stuff. We still have a small failure rate, which we mitigate by testing each screen as much as we can before giving it back to the customer and then offering a 1-year warranty for manufacturer defects on the screen as well.
It's the best we can do--no matter what technology you buy, unfortunately, it's never going to be 100% perfect. You buy from the vendors that are the most consistent and you pay a bit more for a higher quality product. And, as a customer, that's why I always recommend you read online reviews before you take your phone or computer to be serviced somewhere. The good places have great reviews because they take care of their customers.
Both Chinese distributors and some less-reputable cell phone repair stores love to advertise these screens as "OEM." However, they are NOT, because the new glass doesn't come from Apple. It can't, because Apple doesn't sell replacement parts. So, while part of the screen (the original LCD) may indeed be "OEM", the entire screen--as a whole--is NOT. And that is why we do not call it "OEM" and I will publicly call BS on other places that do.
Again: OEM replacement screens do not exist unless you go to an Apple Store. Apple does not sell the parts. High-quality replacement screens with Gorilla Glass are pretty much indistinguishable from the original, but they are not 100% OEM and should not be labeled as such.
You can stomp up and down and say OEM parts don't exist, but they do. Not only that, but phones that are bricked, stolen, or maybe even water damaged slightly could have the screen salvaged assuming it wasn't ruined. They do exist.
Will you be lucky to get an OEM screen, probably not, but my comment was to highlight the fact that what you're saying about parts being 3rd party 100% of the time are impossible.