[LorenPechtel]

Aren't there power delivery versions of HDMI?

I can understand requiring a license for any power wires behind walls.

I could also see the possibility that it's just an old law that doesn't consider data-only cables which don't have the safety issues that wires carrying power do.

[whatevaa]

While HDMI can provide a tiny bit of power and there are active cables for signal boosting, HDMI was never meant for power delivery. You might be mixing it with HDMI with Ethetnet.

[gambiting]

It's definitely an old law that never took data cables into account, but the current interpretation is that any cable that carries electrical current has to be installed and certified by an electrician.