Western classical music has a significant bias toward seven of the twelve possible notes. The notation is an organically grown, highly simplified variation on huffman coding that provides reasonable amount of compression with negligable decoding latency.

This is not primarily about written notation being more compact (though that's a nice bonus, all those 12-tone notations are comparatively unwieldy), but about reducing the bandwidth at which you can meaningfully read. Once you've internalized the decompression step, you will be more efficient than if you had to decode a 12-tone notation. Citation or experimental evidence needed of course, but that's the underlying idea. It's not like past humans where too stupid to try out 12-tone-based notation. It just happens to be less efficient (citation needed again, admittedly, I'm at work and can't actually research this right).

Current notation is certainly not optimal in this respect, I'd be happy to read up on proposals that address the inefficiencies of writing in melodic minor. Unfortunately, I have yet to find a proposal that is even aware of issues of relative orientation and compression.