Earlier quoted context omitted.
Greece wouldn't have been punished, either, except that they were also asking for help at the same time. At least, I don't think they would have...
The biggest reason the EU needed to be stringent with Greece, according to my Greek friends, was that insane levels of corruption in Greek governments meant the government was almost incapable of collecting taxes. Apparently there was a popular video about an area in Athens where the people paid almost no taxes, but an overhead view showed houses with swimming pools.
Of course when the corruption was done by and was in favor of German companies getting some job, all it was well (Fraport, Siemens, subway bribing, etc).
Germany even refused to cooperate to clean things up, e.g.: https://en.wikipedia.org/wiki/Siemens_Greek_bribery_scandal