Using Substandard Parts to Fix Phones

Because my cellphone insurer works exclusively with WeFix I was forced to fix my iPhone X screen with them. Within two weeks the screen started malfunctioning. I took it in and the courteous enough to do a rework on the device. Now less than a week after the rework my phone was in my backpack in a place where it would not be easily exposed to contact. I just threw my bag on the floor knowing that the phone would not be hurt as it was in a zip inside the backpack. To my surprise when I took the phone out of the backpack the had ink on the bottom and a red and green line in addition to the screen being two tone. WHY DO YOU GUYS USE SUBSTANDARD PARTS TO REPAIR OUR PHONES?