No one forces a shop to cut corners. Any shop that cuts corners is 100% at fault for doing so. If the insurer won't pay, you charge the customer, you file a DOI complaint, etc. Lots of things a shop can (and should) do to get paid to complete the repairs as required by the OEM. Collision Hub does a great job of educating shops about this. Educated shops have no problems getting paid for every penny they are entitled to when an insurer doesn't want to pay what they should.

Also, this is not in any way implying that some insurers refuse to pay for things that they should. It happens all of the time. It shouldn't, but it does.