Graham wrote:

It's been said before that plain kilts appear to be more acceptable in America (Hamish may disagree)

Hamish wrote:
Graham, I am not sure what you mean by this!
Hamish, I just meant that while plain kilts seem to be prominent in the USA, you are an exception on account of the many plain kilts you have in the UK.

The notion that plain kilts may be more accepted in the US came from a kiltmaker (not from me), but as I thought about it, it seemed to make sense to me.

I can only say with authority that plain kilts have not caught on in Australia yet.