Yeah this theoretical half-reading of wikipedia always leaves out the practical considerations.
This level playing field lasts right up to the point where each individual government of the Eurozone is mandated to cover the losses of their private sectors, including banking. The days of Germany dictating to their neighbours how their countries should be run are over outside of the ECB and the Euro. If they have a grievance then they can go through the EU courts like Germany did with the Apple case.
Big countries signed up to a common market without tax harmonisation and they would leave if it wasn't working for them, just like the UK did.
Guess which country was forced to bail out Europe's banks and unsecured bondholders in the last crisis? We also don’t benefit by the setting of ECB rates like Germany does, and we're going to get slammed as they rebalance their books following pandemic social payments.
Ireland gets the blame for Apple not paying its fair share of taxes but the issues is entirely a US one: Apple is a US company, yet the US won't force Apple to pay taxes on its foreign earnings. In contrast, if you're a US citizen who resides elsewhere, you're still expected to pay US taxes...
In France the statutory corporate tax rate is 33.3% while the actual effective tax rate is lower than Ireland's 12.5% at 8.2%.
Luxembourg has a statutory rate of 22.5% but an effective rate of just 4.1%.