Automotive power relays are at least a thing, but they're expensive consumables that have significant power draw.
In either case they would have had to add the components at design time and do the physical validation/testing, not ship it as a software update.
Cars were made for 100 years without an internet connection. Even for an EV there is no need for network connectivity or constant software updates. The first time a prominent figure is assasinated with a remote take-over of their vehicle people may start to see this issue a bit differently.
New definition of "absurd" just dropped...