Looking at fraud statistics the vast majority of them aren't caught.
Look at the VAT fraud in Europe, billions lost, virtually nobody arrested
https://en.wikipedia.org/wiki/Missing_trader_fraud
> Notwithstanding these measures, MTIC fraud remains a problem for the EU. As at November 2018, calculations estimating the annual costs of the fraud range from €20 billion up to more than €100 billion (depending on methodology adopted).[21] An EU Parliament study in October 2018 found that MTIC/carousel fraud is the most damaging type of cross-border VAT fraud with an estimated €50 billion losses on average per year.
France is also hemorrhaging billions through social benefits fraud, they don't even attempt to recover most of it as they don't have the manpower