If American companies like Tesla leave the possibility of tracking/disabling their cars remotely, why China should not do the same? It would be strategically stupid to make a product without a backdoor when everyone else inserts backdoors.

My comment above made no judgement about backdoor access to products, it merely pointed out that country X might judge an over reliance on products from country Y a security risk if those products leak information or can be remotely controlled.

It's a risk for China to use US hardware in Chinese network infrastructure as much as it is a risk for the US to use Chinese communications or other hardware.

These risks can be mitigated by vetting but they are real risks that countries must account for in their national security protocols.