I think you might have to factor in both growth and inflation/interest rate.

They're linked since low growth implies low inflation/interest rate, but not always. With globalization, there's possibility of importing deflation from other countries.

In Japan/Europe, you have negative growth, negative inflation/interest rattes, hence low multiples.

In US, you have low-medium growth but also low inflation/interest rates, hence high multiples.

I dunno, not an economist, so just a guess.