I suspected it wasn’t required for
every pilot since most initially licensed pilots will train on airplanes that don’t have retractable landing gears in the first place.
But I guess the technique isn’t much different than if your nose tire blew, which might be included in all training?
Looks like flying with a retractable landing gear is a separate “complex aircraft endorsement” that “has no corresponding check ride or minimum number of flight or ground hours that must be completed.“
(Though that’s what the regs say, the schools that provide it do have those)
https://www.flyingmag.com/guides/how-to-earn-a-complex-aircr...