I don't think they really enforce the switchblade act, do they?
Autos are for sale all over the place
Technically the switchblade Act doesn't apply to selling switchblades within any individual state within the 50 US states. It does however apply to importation into the 50 US states, transporting across state lines for the purpose of sale, and shipping through the US postal system (Title 18). All of which are being regularly violated.
Section 1243 of the Switchblade Act refers to sale and possession, etc, but that reference does not apply to the 50 US states, it applies to what are referred to as "specific jurisdictions". When the Act refers to "any Territory or possession of the United States", that doesn't include the 50 states.
Spyderco got busted by Immigration and Customs Enforcement (ICE) back in (I believe) 2007 for importing butterfly knife parts. That is the last instance of the Federal Switchblade Act being enforced that I know of (butterfly knives being considered "switchblades" under the Act). Spyderco pled guilty and paid a fine.
Considering how easy it would be for a Federal agent to order a switchblade from an online vendor, then wait and see if the knife were shipped through the US mail or across state lines, and what easy convictions they would be, I can only assume they have more important things to do.
I ordered a few switchblades some years ago from a major online knife vendor and received the knives via the mail. That vendor is still in business, and still selling switchblades.
As far as importation, I know for a fact that finished switchblades are being successfully shipped into the US from Italy and China.
Like I said, I don't think switchblades are a high priority for the Feds.