Okay mr. EE. Why don't you check out the real world and see what's involved in accessing the Tesla ECU __AFTER__ the car has been assembled. You either don't get this point, or are being deliberately ignorant.
Here, this might help (this is how you access the MCU - not 10 minutes) :
And this is what's inside the MCU (skip to the 2:08 mark):
Yes, the second part __might__ be a 5-minute swap, and where your comment would be relevant, but you've missed the entire first part of tearing out the dash to get the MCU!
Does that clear it up yet?