What is stopping car companies to do something similar to car batteries for safety or performance reasons?
It is far easier for a manufacturer to control a car and its lifetime with EV and modern ECU stack .
They do not need to allow anyone else to access either . Even the RTR movement is more cautious in asking to be able modify road cars on the road, it is one thing to be able to repair your own tractor , it is another thing when the safety of others on the road .
Automakers can get away with lot of things by citing safety .