But two weeks of dev time for every municipality adds up quickly.
The issue is that germany is deeply federated, different decisions are made at different levels. This could translate well into software by having the higher levels create interop standards and reference implementations that allow for plugins while the lower levels use the reference implementations (with plugin extensions for the myriad of special of special cases) or just implement their own according to the standard.
But unfortunately it doesn't translate because the german state either picks the cheapest contractor (which almost always leads to blown budgets and delays) or they pick by nepotism.
They are also dead set on waterfall projects and don't seem to realize that if they keep blowing budgets anyways, that might not be the best strategy.