I don't have a Tesla, but I have a Zero Motorcycle (electric, doesn't have OTA) and I can tell you most updates you don't want right away. I'm guessing Tesla is no different.
I don't want a machine I depend on to change its behavior out from under me. I don't trust the manufacturer to make only changes that are in my best interest - or, more simply, to only make changes which suit my preferences. I would rather evaluate the machine before I choose to buy it, buy it as it is, and feel secure knowing that it will continue to be nothing more and nothing less than what I bought, unless I decide I want to upgrade or change it.
sorry were you under the impression it updates without you asking? I am given a prompt if I would like to upgrade, and it has a list of component changes. Also, your car is likely updated at the dealership unless you specifically ask them not to update, in which case, you could just not do the tesla updates.
What happens if you say "no"? Update systems generally seem to just nag you relentlessly until you give in and accept whatever the designers want; does the Tesla system actually go away when you tell it to? If so, then maybe I wouldn't hate it so much.
I've never actually taken a car back to a dealership.