This is a picture from a local Stationers window. On the Right you can see a calculator. In the centre, standing up is a can of pepper spray. To the left is a taser gun. All around are various trinkets including a car, fan, cash till etc.
Thankfully, in the main, San Francisco is peaceful and I do not feel the need to carry any protection. There are areas I would not go, especially at night but then, I hesitated to go to Hatfield Town Centre in the evenings. One of my Lodgers was robbed three times there.
However, it is an interesting reflection on what is socially acceptable here compared to the U.K.