@feld brew never puts anything in /usr/bin directly, and /opt/homebrew/bin are all symlinks:
/opt/homebrew/bin/python3 -> ../Cellar/python@3.12/3.12.2_1/bin/python3
vs
/opt/homebrew/bin/curl -> ../Cellar/curl/8.7.1/bin/curl
But, I suspect @sun is correct to some degree, that brew won’t override OS installs automatically, and will want you to work for it.
Also just a guess on my part :)