Fact is these 3rd party displays are the exact same as Apple’s, and even come off the same factory line. It’s just the fact the serial numbers haven’t been logged by Apple (ie. the Apple tax hasn’t been collected). Hence Apple being vindictive with these messages, etc.
Having worked in mobile phone sales for years, I can tell you that many repair facilities use subpar parts and tell their customers that they’re ‘genuine Apple parts.’ Working for a company that is now an Apple Authorized Service Provider, I see firsthand what training people have to go through and how many extra steps are required to do things the ‘Apple’ way. Training goes over how to interact with Apple clients and what can and cannot be repaired and what must be replaced. Personally, I’d rather have a new phone or motherboard than a device someone has taken a soldering iron to, especially if it means I’d have less likelihood of failure. Today’s devices are created with much smaller solder points, etc.. and I’ve seen some pretty horrible hack jobs on much larger devices. For the extra few dollars, although it may seem stupid to some, I’m all for every screw and gasket being replaced as part of a screen or battery replacement. I know that the exact torque requirements are being met because every repair specifies a specific screwdriver with that exact torque setting, and when the screen is replaced, it’s being pressed with the exact amount of pressure across the entire device for a specified amount of time, and once that is completed, it’s run through diagnostic tools, which, yes, do reset whatever magic software wizardry Apple puts into their devices to verify repairs. But you know what? If something goes wrong, that same tool will give you an error and make you take it all apart and replace everything over again with new parts... so it’s not just resetting a counter with a 1 or a 0 to say ‘genuine Apple repair.’
That ‘Apple Tax’ you refer to.. it includes replacing every single part you remove if it can be worn in the process of removal or replacement. It includes gaskets, screws, individual training documents with images for each and every step, specific little tiny screwdrivers with specific little bits for just the right amount of torque required in every step, display presses, device sleds for each device to fit into that press, servers and computers to maintain all the updates and diagnostic tools at a local level, and a worldwide warranty that means it’s guaranteed to be done right, and if something goes wrong, you can get it repaired at any Apple Authorized Service Provider.
The Apple Tax doesn’t seem that much when the local cell phone repair shop in the mall and isn’t ‘certified’ only charges $10-20 less for a screen replacement with a screen that is visibly less clear, with imperfections, and funky coatings.. all glued in with some random stretchy black goop that is coming out of the seams and gives an error when you try to use TouchID, requiring you to go back and have them fix your phone again. *shrug*