Is 91.175 enforced in the USA?

Peter wrote:
This is the reg which prevents flying instrument approaches unless it
is a published one.

In the UK, this is not illegal (on G-reg aircraft). But then we don't
get the radar services here, etc. Pilots tend to fly descents using a
GPS, etc.

In the USA, there are GPS approaches, and there are many more
instrument approaches anyway.

At the *practical* level, I am curious to what extent the FAA enforces
this regulation. I suppose this question is relevant only in the
context of airports which don't have a published IAP - I don't know
what % this is in the USA.

I have a hard time imaging a pilot would want to fly a homemade GPS
approach.

-Robert, CFII