Comment by olowe

Plan 9 (a Bell Labs successor to Unix) did away with the whole bin, sbin, usr/sbin thing and its shell only looked in /bin. How things got into /bin is a different story.

For me this was an eye-opener. I kept trying to wrap my head around all these different paths and "standards" because I thought it was correct and deliberately designed. Looking back through the history this doesn't seem to be the case; I feel much better for being confused by all the different PATH conventions and strict hierarchies.