MAC ids on network and motherboard interfaces are often in EEPROM and capable of override for spoofing purposes. Some vendors use a MAC ID as a license key. That was viable when the manufacturer generated an immutable key for the network interface. That's not the case anymore.
Finding ways to track your activity will be a perpetual cloak and dagger effort. New ones will crop up soon after you've nailed the ones you discovered.
“Finding ways to track your activity will be a perpetual cloak and dagger effort.”
I think you’re correct. You know more about what’s going on inside those boxes than I do.
My company’s IT department is all the time fiddling with security software and training.