> You can't get any high value notes there, they just don't exist
Yes, although this is mostly by capping the highest regularly circulating note at £50 after the war and then waiting for inflation.
> And there's so much street crime,
[mostly false]
> and the police care so little about burglary,
Sadly true (including "find my iPhone" reports; there was a joke during the Mandelson scandal that this was the one time the Met had managed to locate a phone)
> The UK did this already and ML is out of control there: criminals just don't care.
Yes, which makes a sort of orthogonal point about whether or not cash is actually important for this. There's the conspicuously suspicious businesses ("American sweet shops"), but also more complicated stuff going on (Scottish Limited Partnerships were in the news). Then there's all the Crown dependencies, which are a total financial wild west still.
> Carousel fraud in the EU is a huge problem that governments hate to talk about because they don't know how to fix it
God yes. This is a significant problem in VAT as a concept; I don't understand why the EU loves VAT so much.