Because you can easily pocket more than a couple of grand cash in hand - the issue is traceable things like buying cards. A families grocery bill is more than a couple of grand a year - you think you can’t spend cash at the supermarket without getting caught? The issue is large sums 10k+ are harder to hide. But implying 1-2k is the limit is completely unjust. I’d you bought all your food, nights out, clothes etc through cash in hand that’s not what gets people caught. It’s buying cars, property, gas bill, putting in the bank that does. Think how much you spend a month that you could do via cash - that’s how much they can hide. It’s a fuck lot more than 2k.