The government pretty much accepts that certain categories (say, dentists) hide a lot of their profits. Instead of fixing this, they decided to just assume you are hiding ~60% of what you declare and tax you accordingly.
A few years later they decided to just create a table of what each professional from each category should earn and if you declare less than that you can expect an extremely unpleasant visit which WILL find something wrong with your business.
Law-abiding people get crushed under this weight, while tax evaders just declare even less (or even operate completely outside of the law). Good people get punished, bad people don't. Going to the authorities to report these people can be successful, or unsuccessful, or frustrating, or very unhealthy. Feel like gambling?
After 10 years of this you start wondering if you're the idiot. You can become one of the "furbi", or keep trying to work in this broken framework, or leave.
I left.
Oh and the tax code is so byzantine you need to pay a professional even if you have an extremely small and simple business. And even they make mistakes. And you get to pay for those mistakes.
You all should just reform the Holy Roman Empire... ;-)
</sarcasm>