This is not completely true, it only applies to students from other EU/EEA countries. There are some exceptions for a few other european countries but apart from those, international students still have to pay the tuition.
This is incorrect (for Germany) unless you want to go to a university in Baden-Württemberg (one of the 16 states of Germany), which introduced tuition for international students in 2017.
Everywhere else you will pay virtually the same fees[1] as a German national (<1k euro/year), except that you may be required to pay into a 'security fund' for international students if you have the means, which helps less-well-off international students or those who have fallen on hard times to pay those same fees.
Take the TU Berlin as an example: https://www.tu.berlin/en/studying/studienorganisation/finanz...
[1] Note that these fees are not tuition. About half of them pays for a greatly discounted public transport ticket, the other half for an assortment of smaller things.
The government wanted to make foreign students (outside of EEA) in universities pay significant tuition fees but that was shot down as unconstitutional because the constitution states that public education has to be free for everyone and anyone...