Many four year colleges have stated automatic admission by stats criteria, so they can be safeties for applicants who have the needed stats and can afford those colleges.
Regarding yield protection, an analysis of CDS-based information a little while ago found that level of interest consideration was 29% yes / 55% no for public colleges, but 57% yes / 23% no for private non-profit colleges (both groups had colleges that did not fill in that information).
http://talk.collegeconfidential.com/discussion/comment/22085702/#Comment_22085702
Of course, for the vast majority of prospective college students, money is the main constraint on college choice, so it determines which (if any) colleges can be safeties (or financially realistic matches or reaches).