Are you sure it doesn't*?

* When we treat different versions of say, the MIT license, with different names and copyright years inserted, as different licenses.

I have to imagine the file would compress extremely well though... I'm more curious why they don't use compression.

Not sure why Apple doesn't offer a compressed filesystem :p it makes writes a bit slower when compression fails, but otherwise the savings in I/O time often makes up for the increased processing on read and write.