Japan
Canon
Canon changed mounts twice — FD to EF in 1987, EF to RF in 2018 — so lenses from the film era need adapters and lose automation. Factory service for film bodies has ended.
The FD mount that the AE-1 Program uses was abandoned when autofocus arrived. That made FD lenses cheap on the used market, and it means they stay manual-focus only on anything newer. Current RF bodies take EF lenses through Canon’s own adapter with full autofocus, which keeps the used-lens pool large.