In most push to start modern cars, it isnt really one central computer like how cars used to be. You still have an ECU, like the computer that is relevant to the drivetrain. But then you also have one or two others separate units that have to have authority over the ECU by nature because of other things they do. Like if the unit that communicates with your key to say “its okay to allow you to use the car” doesnt have authority over operating your powertrain, then it would be much easier to steal your car (i.e. kia and hyundai from a certain period of time). In many cars it also monitors engine performance and can make live adjustments to the operation of the engine, prevent some catastrophic failures, etc.

So having some smarter computer aspect of your car rule your powertrain is a pretty good security and operational thing, even if it leads to the potential for inconveniences. Like if your electric key dies you could lose the ability to start your car, which would never happen with a physical key

That said, I think all updates for cars should be done at dealerships, and not be an over the internet type of thing