Axel Rauschmayer made a list of small bugs in Apple’s products

And you have to admit that it's not very satisfactory for an OS to have issues with filenames that include not-so-unusual characters like colons.

This is 2020, not 1975.

OK, something something backward compatibility. But even so.

And there are more bugs - for example the image view in Finder ignores the window frame. Instead of making all the previews fit in the window frame ready for vertical scrolling, it dumps them off to the right where no one can see them without horizontal scrolling.

The drag-and-drop autoscrolling in Finder is annoyingly random if you want to drop something into a folder that isn't currently visible.

Dragging the left divider of a file preview in Finder doesn't resize the preview - it just moves it to the left or right. There are very few use cases where this is the most useful behaviour.

There's no obvious "expand width to make filenames fit" option for the dividers in Finder. (You can double click on the divider. But if there's a setting to make the width auto-size by default, it's well hidden.)

Exporting photos from Photo won't let you save a photo with a custom name. You can pick a folder, which is nice, but no "Grandkids Christmas 2019.jpg"

Time Machine often doesn't work.

And so on. These are all avoidable irritations. They wouldn't take long to fix, and they all add up to create the impression that Apple doesn't really care about core software quality or UX.

From the user/UX POV, they absolutely are. They may not trash your file system or set your Mac on fire. But the UX is the public face of the product. If it has issues and causes unnecessary friction, that reflects badly elsewhere.