I think that's half of the system that Colorado is opposing? Test scores (not so easy) reflect income more than aptitude. Not just the 'legacy' checkbox.
Hard test scores reflect some sort of aptitude at least. The fact that higher income students get them is a second order effect with many many causes that need to be addressed separately.
Legacy checkbox reflects absolutely nothing other then nepotism.
But they're dealing with the problem at the stage of the pipeline which they can address, which is a bit late as inequity begins to solidify long before.
Some children will have AP credits and some wont. Some children will have completed calculus and others won't have started. By this time, years of advantage and disadvantage have already accumulated. These differences in student profile will interest both in-state and out-of-state colleges.
zulu314 is pointing out that tests can be meaningfully designed for predictive value, and I would additionally wonder whether universities all around the world will follow suit by diminishing test importance?
Legacy checkbox reflects absolutely nothing other then nepotism.