If you're self-employed the tax rate is ~70%, at least for lawyers in germany. Source: My self-employed gf.
And no, she does not earn 5 figures, 4-6k gross per month with 1 part-time employee for the bureaucracy stuff (bills, phone service, faxing, scanning etc.). With a 60 hour week.
Your girlfriend does not pay 70% tax. This is mathematically impossible if you actually look at all tax rates.
Even under a charitable interpretation this is simply wrong.
I suppose you have no first-hand experience, but have read that on social media?