I'm a local truck driver for a smallish local trucking company. My company installed new dash cams with both internal and external cameras. Every truck I know has at the internal camera at least covered in tape, if not removed completely (Mine is gone completely). If my company required the internal cameras, at least half the fleet would likely quit and it would be catastrophic for the company.
One of the perks of the job is being alone and just chilling out most of the day. You don't get to watch me.