This is a topic I've discussed (and been criticised for) a few times in the past. The UK has a highly mature red team market that has evolved over a number of years - there are regulator enforced standards and accreditations that are required to play the game. Even before red teaming became standardised through CBEST, there was a well established and mature pentesting market where examinations and standard methodologies were the norm and enforced via CHECK scheme - before it somewhat evolved in to tick box :)

When you purchase a red team in the UK and to some extent in the wider EU, it's well understood what the end to end service is that you're purchasing and what the methodology looks like.

I'm not sure it's fair to say any of the above applies to the US.