When a moral panic happens, a lot of things get blown out of proportion. A good example was the panic relating to D&D and satanism. There was a huge panic sometime in the 50s or 60s about the police dealing with young thugs with concealed switch blades, which could be hidden, and then deployed one handed so fast a cop couldn’t draw his weapon fast enough. So this panic got a lot of laws drawn up to ban any switch blade.
Since then, the there are knives that skirt the law by not having a spring which force the blade open, instead a tension bar. There are still types are illegal to carry if a Cop would find out you have it, like “Out the front” switch knives.
The stupid part is, there are plenty of “one hand deployable” knives on the market that are 100% legal. But the laws never get revisited. In my state it’s illegal to have a out the front switch blade, yet a bunch of high end OTF knives are for sale at a sporting store. They just post a sign that says “Know your local laws”, which some how makes it okay to sell.
If anyone has more to add, or corrects, let me know.