so if miners are not equal, perhaps pools should be segregated? detection and enforcement would need to be worked out, but much more complex systems exist in this world
Not sure what you mean by equal. There is no requirement to use all possible nonces. It doesn't allow them to cheat or gain a disproportionate share of the reward. It is also dynamic. Two different ASIC chips from the same company many not cover the same portion of the nonce range.
I think this is a misunderstanding of most users that you must check the entire nonce range to be doing as much "work" which is wrong. It's purely the number of nonces you check, even if they're from different work.
Very little hardware actually checks the full nonce range. Many abort work on the first nonce they find while others have a matrix of nonces they're likely to check and miss others (there is nothing invalid about doing this, nor is there any way to make this sort of practice find less blocks).