Then it's too late. Code requirements would prevent all of this. Requiring county inspection to certify insulation install (presence, no gaps) and thickness (R-value) with a post-install test. All of that would increase costs and build time though.

If you do something wrong you need to correct it at your cost, including everything. I've been in framing before and called to move a joist that we put right where the toilet pipe had to be. We moved it, but it was a lot of work to cut all the glue and get it in the place it should have been. (normally joists are a fixed distance apart, but we are supposed to verify on the print before hand that the toilet or other pipe won't land on one). At least the plumber called us - he would be in his right to just cut the joist, and then we would have to fix it after the house failed the final inspection.

Contractors try to look after each other. Most know enough about other trades to stop and say "this isn't right, are you sure you want me to continue" if someone else did something wrong. But everyone once in a while this fails.