It's a lot more than "basic testing" Andy. And standards DO matter. The British Standards, IMHO, are best standard in the world, far in advance of CE Euro standard (corrupt) or USA DOT standard. (lots of helmet industry experts agree Brit standards are overall best)

USA also have SNELL standard, which also involves comprehensive helmet testing, which I witnessed when I did an article on SNELL some years ago. Spent a day at their facility in Sacramento, CA documenting the testing they do and recording two hours of interviews.

The main thing I got out of the SNELL guys was that companies like Arai and Shoei are much more invested in helmet safety and technology than some fly by night, year old Chinese company. NOTE: big difference between Chinese helmets and Korean ... mainly HJC. Korean HJC are highly rated world wide in all testing.

Arai and Shoei have their own testing facilities, and according to
the SNELL guys (who've visited both companies at least a half dozen times)
the testing and results are proprietary ... and they (nor anyone else) is allowed access to their testing or data.

But it's true, even cheapo helmets will protect you fine ... most of the time.
And you're right, much of it is marketing driven, image and style up front. And Plush interiors and Hip graphics seem to sell helmets more than anything else.

I just know I'm glad I was wearing my very expensive Arai R-7 when I took a flying leap off a cliff .. and landed on my head!
Other than forgetting how to speak Spanish for a year ... I was "mostly" OK!