Whether it be electronics, automobiles or medical equipment, the manufacturers should not be able to horde “oem” parts, render your stuff useless if you repair it with aftermarket parts, or hide schematics of their products.
Summary video by Marques Brownlee
Great channel covering and advocating right to repair, Lewis Rossman
Basic blender went bad (motor ran but spindle wasn't rotating). I wanted to disassemble to see if it could be repaired. Three of the four screws were Phillips head. I had to cut the casing open in order to discover why I couldn't unscrew the fourth. It was a slotted spanner.
Grinding a notch into a flathead screwdriver is annoying but it'll still work fine as a flathead even afterwards. I would probably just grind the bulge out of the screw though.
In this case the screw was at the bottom of a narrow slot, and they only found it after breaking things.