[Spooky23]

The problem lies in that you're pushing the problem into the hands of anonymous cable makers and clueless end users. It's really difficult to stick a standard plug into a 30 amp socket.

It's really easy to buy some substandard USB-C cable that lies about it's capability.

[Johnny555]

The same issue would exist with any universal in-wall DC power supply -- if consumers buy a substandard product, it can destroy their device. Unless you want separate ports different voltage/power output then the user has to buy separate cables for each one.