> I help to run and it's very complex.

Most of the complexity comes from a backward compatibility and the fact that politicians creates exceptions for certain products to gain votes. If the tax was the same for everything it would be much simpler.

Fraud is a solved problem, especially if you can start from a blank slate like in US. Governments are trying to reduce the fraud, but they are super slow. https://en.wikipedia.org/wiki/SAF-T