Of course they are. I expect the number of furlongs in a whatsit has changed at least every week. Who could even pretend to remember the actual values?
Furlongs is a different measuring system all together. Same with miles and inches. We don't convert between those measurements because it's not necessary.
To add to that, US customary is a collection of measurement systems with different purposes. Most of the jokes about the US measurements are about the "silly" units like furlongs and acres and whatnot but those are either not at all part of the US customary system or are used to measure different things and are not converted between. Like, there is no reason to measure distance in inches when miles do fine. Anything using precision use a different system altogether or a variation on us customary that is often favored over metric for precision. Not that US customary is better than any other system, just it's not really as bad as people make it out to be. It's perfectly serviceable and changing away from it is not really the top of the priority list for this country.
Maybe a mistake NASA made 25 years ago is less influential on the ongoing crises plaguing the US like gun violence, civil and political unrest, and countless other issues are also on the list of things that need to change. Seems silly to argue about how civilians in a country weigh things when those civilians don't have water because their government gave up on fixing the infrastructure to provide that water in several major cities. You want national change from a country that's trying to find out if the potential next president will follow through with promises of being a dictator? Cool bro.