Why do plane kits from the US still use Inches?

This makes them non-standard from the rest of the world. I have a Funtana40 and the screws are non-standard. I will have great difficulty obtaining things like 6 32 screws etc. What is even more annoying is trying to find an imperial (non metric) sized hex wrench!!!

I know that US RC Heli manufacturers have started to standardise on metric thread sizes. So there is no need to keep with inches and feet.

Anyway just wanted to sound off a bit. This post will probably change nothing.