Except, of course, you, and me, and just about everybody else understands that Greece is neither able nor willing to ever pay that money back.

It's not able, yes (it's elites are very willing, it's not like they're going to pay for it) but that realization and the actions that should follow it were never allowed to be articulated, and no policy implications were drawn from it. Quite the opposite, the whole episode was used as a time saving device so the ECB (i.e. the EU taxpayer) could be burdened with the private debt of German and French banks, so it could default at taxpayers expense not the bankers.

Germany ran "austerity" politics for most of its recent history

No. Germany had austerity of the type we're talking here under Heinrich Brüning, AFAIK, and the results of that are well known

But in order to restore a primary budget surplus it's the standard treatment

What? destroying democracy? And why is a primary budget surplus more importance than independence and why does it make mass suffering OK? And again destroying the economy worsens debt and destroys much more than the current economy. One has also to look beyond first order effects...

The road of excess leads to the palace of wisdom - William Blake