Part of this is no national chains are on MacOS (Walmart, Kroger & ilk are on Suse w/SuperPOS Ace, Costco just switched to Windows using an oddball NCR product), and few megacorps have gotten big on MacOS in a way where they develop IT talent that deeply understands MacOS. Thus, the pool of talent is extremely small, and the ability to self teach (closed source software and all) is really limited.