2023 Tahoe High Country is gone...

[BlaineBug]

I used to be a GM tech and a service advisor. I would NEVER ask a tech, nor would I as a tech, drive a customer vehicle at illegal speeds just to satisfy a customer complaint. It's their ass if they get stopped by a cop. Also, what happens if the tech totals your car doing 80MPH, is that fair to endanger their life and/or career? Do you really think a cop will just say 'it's ok for you to travel at illegal speeds because you're a dealer trying to duplicate a customer concern'? Not all states allow for speeds over 75 MPH.
I do agree with you that more checking of your vehicle should have been done, but your expectations are crazy expecting someone else to drive your 6000 pound at dangerous speeds.

This is just my opinion of course.

Lawsuits and liability. About 30 years ago one of my grandmother's cousin's children was paralyzed from the waist down during a test drive in which her boyfriend was driving, something about the salesmen suggested the boyfriend drive fast or something. She got a hefty settlement and the dealership closed up shop. When the boyfriend left her I heard she sued him too. So, she lives in a large home but rides around in a wheelchair, last I saw her maybe 20ish years ago. Ouch.