OS X :: File Names Not Case-sensitive?

Every unix system that I've worked with has had case-sensitive file names. In other words, file name "foo" is different than "Foo" is different than "FOO" and so on. In the MAC OS X shell,

if I have a file name FOO, and I type "more foo", then the contents of FOO are displayed, instead of an error message saying "foo not found". It also means that I can't really create files "foo" and "FOO".

Is this something that Apple has implemented on top of unix? Is it possible to get around this, so that the names do indeed become case-sensitive? It doesn't seem like an inherent unix thing, because if I type "f <tab>", and the only file in the directory.