If I recall they are called Heim joints because that was the name of the man or company that invented them. Much like a vacuum cleaner (especially in the UK) is called a Hoover. So I just looked at Wikipedia.
The spherical rod end bearing was developed by
Nazi Germany during
World War II.
[1] When one of the first German planes to be shot down by the
British in early 1940 was examined, they found this joint in use in the aircraft's control systems. Following this discovery, the
Allied governments gave the
H.G. Heim Company an exclusive
patent to manufacture these joints in
North America, while in the
UK the patent passed to
Rose Bearings Ltd.
[2] The ubiquity of these manufacturers in their respective markets led to the terms
heim joint and
rose joint becoming synonymous with their product. After the patents ran out the common names stuck, although as of 2017 "rosejoint" remains a registered trademark of
Minebea Mitsumi Inc.,
[3] successor to Rose Bearings Ltd. Originally used in aircraft, the rod end bearing may be found in cars, trucks, race cars,
[4] motorcycles,
[5] lawn tractors, boats, industrial machines, go-karts, radio-control helicopters, formula cars,
[6] and many more applications.