[jprd]

Great points!

To add, also take into account that there were almost no state school CS programs until not that long ago. Many of the graybeards I learned from along the way had English and Music degrees, they autodidact-ed the rest through trial/error and collaboration with peers (and official systems manuals).

These are the cats that ran anything from VAXen to high-end CAD workstations and whatnot, wrote internal mission-critical applications with no formal CS background. Just passion.

Take also, the generation of COBOL jockeys whipping up reports and maintaining ancient stuff (also mission-critical) who learned on the job and were never taught algorithms and beyond.

Even at the AMZN gig mentioned by OP, whatever he was working on was a cost-center. If a team at that level can create its own stack, guidelines and the like, mistakes will be made.

Fixing that requires investment, and I can't imagine that any resources were invested in that app, because cost-center.