If it’s not built to code to code it can pose all sorts of safety hazards to your neighbours or future owners of your property. If you don’t bother getting approval you didn’t bother building it properly either.
At the slightly more silly end, your shed could lower the value of the neighbours property (because it looks like a meth lab, or just a general hillbilly grotto) and the law holds financial harm higher than physical harm most of the time.
Apparently the average is up in Germany, you just haven’t had any extremes this year.
https://twitter.com/rarohde/status/1688486834890854401?s=46&t=041FqqqpppFjW7CoNV9wDw