You’ve probably spent an hour hunting a bug that only exists because of two letters: readme.txt vs. ReadMe.txt. It’s infuriating. And it’s completely unnecessary. Apple knows it. They actually tried to fix it. They failed.
When Apple designed APFS, the new file system for macOS, they had a choice: make it case-sensitive like Unix, or keep the old case-insensitive behavior. The engineering team pushed for case-sensitive. It’s cleaner, more correct, and aligns with the Unix heritage Apple claims to love. But then reality hit: thousands of Mac apps would break.
I’m not talking about obscure shareware from 2004. I’m talking about Adobe Photoshop. Microsoft Office. Even some of Apple’s own apps load resources using the wrong case—image.png when the file is Image.png. On a case-sensitive file system, that’s a crash. Not a warning. A crash.
Apple did the math. They could have forced every developer to fix their apps. Or they could throw away the engineering purity and keep the ecosystem running. They chose the latter. APFS is case-insensitive by default. The dream of a clean, modern file system died because of a thousand small sins.
This is the hidden tax of backward compatibility. It’s not an abstract concept. It’s a real, concrete anchor that stops a trillion-dollar company from doing what’s technically right. Backward compatibility isn’t a feature. It’s a tax on innovation.
And here’s the twist: Apple is the most controlled ecosystem on the planet. They own the hardware, the OS, the app store, the developer tools. If anyone could enforce a clean break, it’s them. Yet even they couldn’t. The dead hand of the past is still typing.
Every developer who has ever muttered “why can’t they just fix this?” now has an answer. They tried. The weight of twenty years of apps held them back. That’s the real story of innovation in 2025: not what we build, but what we can’t tear down.
So next time you wonder why your Mac still treats “File” and “file” as the same thing, remember: Apple wanted to change it. They couldn’t. And neither can you.
FAQ
Q: Why didn't Apple just force app developers to fix their apps before switching to case-sensitive?
A: Because it would break millions of existing installations overnight. Apple judged the user experience disaster of crashing apps worse than the technical debt of keeping case-insensitivity. It's a pragmatic trade-off, not a technical failure.
Q: Does this mean macOS is forever stuck with a case-insensitive filesystem?
A: Practically, yes. The number of apps that depend on case-insensitivity is too large to ever fix. Even if Apple wanted to switch in a future macOS version, the transition would be a nightmare. The decision is essentially permanent.
Q: Isn't case-insensitivity actually better for normal users?
A: For most users, yes. It prevents confusing errors. But for developers and Unix compatibility, it's a constant source of bugs. The real problem is that Apple tried to serve both audiences and couldn't fully satisfy either. The compromise satisfied no one.