The problem is that I'm not talking about getting +1300 EUR/month situations, but about +300 EUR/month situations.
And suddenly you have to explain your finances to the bureaucracy and... you still have to earn +1000 EUR/month in addition to the bureaucracy needed so you get to keep at least some of it (without committing social security fraud, ofc).
It's not that bad if it's steady; but if it's fluctuating you easily spend a couple hours each month. And for at least some people, that type of work is far worse than their occupation of choice.