But they are all pretty similar, even if they don't admit it... ;-)
I think, from a user's point of view, that's kind of true - at least of the last 10-20 years or so. Back in the 90's it was less clear (as Windows 3.1 was way behind most of the competition).
Believe me, though, from a developer's point of view, different OSes are completely different. You've got different kernels, different multitasking paradigms, different methods of UI, all sorts of things. Programming AmigaOS is a pleasure - it's all nice and simple, logical and well thought out. Programming Linux depends on which toolkit you use, and to be fair I've not looked very hard at it (but the X system is awful) - and then there's the monstrosity that is Windows. The words "WM_PAINT" still strike fear into my heart now, as do the initials "MFC".
When you get under the hood, you realise that the different OSes can be very different... it's just hidden from the average user to make them all
look the same.
