Frankly, I don't think anything is more dangerous than gasoline, and people buy tons of that. Why Germany should restrict KBr escapes me except that bromides will put people to sleep. It might have an illicit recreational use. Possibly bromine can haloginate organic chemicals used in the manufacture of street drugs. They restricted the sale of iodine crystals in Calif. because people were using it in some recipes for meth. But silver nitrate is a very useful chemical. The danger to the public is slight.
Here in Oregon, we're not allowed to pump our own gas (which I'm just fine with!) Pumping your own gas is crazy, nuts dangerous .
The goofy quirks of people's notions, and the regulations that end up codified around them can be a serious annoyance and nuisance, but they also help keep the globe from becoming completely homogenized. Keeps things interesting.