There has been much court action in the US of late regarding repressive knife laws; I believe balisongs/butterfly knives have been legalised in Hawaii lately.
For those interested, a link to an organisation that monitors such things:
https://www.akti.org/
I have recently become enamored of automatic knives, and now have too many. I find some of them to be very useful; having a decent blade that can be accessed and withdrawn with one hand is essential for some handicapped persons, as well as the common run of mankind. My current favorites are those whose blades are driven out the front of the handle; the nature of the mechanism makes them extremely safe to carry, and the action is such that exercising it for its own sake is a constant source of amusement.
There are many that are in fact veritable works of art; exotic materials, artful blade architecture, and machining to extreme tolerances. It's a shame that such objects are subject to restrictions, but governments always seek increased control, often to the detriment of common sense, as well as to the citizen/subject.