The tests done on the buses showed that they can be stopped as well as otherwise controlled remotely from China. This is way more than diagnostics, and remote control is _not_ something which is common in road vehicles.

Having "a sim card" is less than saying your car "has an on-board computer". In no way does that imply remote control.

Even you admit that most of them aren't for remote control, so what are you agreeing with?

Remote control is just one over the air update away.

International politics does matter. So, yes, a country that is historically hostile, or allied with countries that are hostile, towards yours, gets different treatment.