I can't speak for European tax rates...
but here, the more one makes, the higher percentage one has to pay. This is called "progressive" to use a high-sounding phrase. I have no objection to everyone being taxed at the same rate, but I can see no rational justification other than the greed for tax revenue to charge some people a higher rate simply because they earn more.
The system has gotten so distorted here in America that the bottom 50% of tax payers only pay about 5% of the tax revenues. As a result, income redistribution schemes are popular with millions of voters because they're voting to take money from others to give to themselves.