In the same note of tech in trucking, the large truck manufactures have started 'John Deere-ing' their equipment and making more electronically integrated, non user replicable, non-standard parts.

The newer parts typically are lighter, which means less fuel usage and room for actual cargo. At the same time, if the part breaks in 100,000 miles and costs an arm and a leg to replace the owner/operator doesn't gain anything but paying the manufacture more of an ownership tax.

the trucking market is so big, I wont be surprised if people would just make aftermarket parts.

If you have 3D printer or CNC machine or injection molding, these parts can be made DYI, to the spec.

for example Tesla charges $1000 to replace a broken passenger side mirror for model Y.

I got aftermarket mirror for $200. I think its a no brainer to use aftermarket part and dont pay 5x markup to the richest man on the planet