[12_throw_away]

IME, CORS is pretty straightforward in prod but can be a huge pain in dev environments, so you end up with lots of little hacks to get your dev environments working (and then one of those hacks leaks back into prod and now you have CORS problems in prod).

[reactordev]

This. This is a result of not having proper environments and engineering practices in place and so the team or engineer is free to just wing it and add hacks around security best practices because the Security Team (tm) is elsewhere and they never understand the ask. They know PKI and certificates, access card identity, maybe Cisco for their "cyber security" but that's usually where it ends. Yet somehow, they are in charge of CORS and TLS and Sast/Dast scans and everything else that should be baked into the pipelines and process. Resulting in an engineer saying f'it and adding an `if localhost` hack or something. CORS is one example but there are many others in pretty much every area of security. OAuth, CORS, LDAP, Secrets, Hashing, TOTP, you name it. Each has a plethora of packages and libraries that can "do" the thing but it always becomes a hairball mess to the dev because they never understood it to begin with.