How can merit aid not benefit students? Just about everyone I know will send their children to a private school with merit aid. The better the offer, the greater the likelihood they will attend. Almost none will send them to a private school with no aid at all.
When we actually looked at the costs, plus what is included in the private school tuition that we are now currently paying for, like music lessons (even with a fee, those are a bargain at the private schools), the packages that include merit aid will probably cost less than a UC with an additional year needed to graduate plus the added cost of apartment over 4 years in a dorm or on-campus housing.