Purely anecdotal, I noticed there were far more people in fancy cars going at ridiculous speeds in ridiculous stretches of roads with loads of pedestrians and cyclists around when I lived in Bristol compared to the Netherlands. I called them CICs: "Cunts In Cars".
Road design probably plays part in this; a comparatively wide fully asphalted road probably isn't the best design for 20mph. Traffic calming and all that.
It's a prevalent attitude of successful people who are used to lower ethical standards applied to them and being given priority in their day-to-day life. An extra factor is that premium cars (irrespective of wealth) are sought after by people with negative personality traits [1].
I don't know why the difference between UK and Netherlands, maybe due to differences in income equity and judicial fairness? I imagine the behaviour is worse in countries with worse social fairness (Russia, even US?).
In my observation, in the Netherlands someone with a flashy car is quicker seen as a show-off. Generally speaking, it has a somewhat more grounded and egalitarian culture. Someone calling themselves a "Baron such and such" or "Sir so and so" like they do in the UK? The entire country will roll their eyes.
In the UK, it's somewhere in-between the mainland European and American attitudes, where someone with a flashy car is seen as deserving of it through their hard work.
And not everyone who drives like an idiot has a flashy car by the way; lots of those pumped VW things and whatnot as well (in both countries).
Road design probably plays part in this; a comparatively wide fully asphalted road probably isn't the best design for 20mph. Traffic calming and all that.