This is kind of a chicken and an egg situation: people wouldn't apply to as many schools as they do now if they were more confident about their chances (I most certainly wouldn't apply to the 20 schools I did - who wants to spend all the money?), but, of course, part of the reason it's so hard to get into any individual school is because so many people apply to each school.
I realize that getting into any medical school is a privilege nobody is entitled to. Still, there is something deeply dissatisfying about the process where some people can sit for months on 10+ acceptances while others hang in the wait list limbo in hopes of a single acceptance. One can argue that some applicants are just better than others, which is, of course, true. But, barring a few all-around stars and a few painfully socially inept people, it seems to me that applicants invited to interviews are similarly strong for each individual school. So, while preinterview selection kind of makes sense to me (objective/"objective" factors like stats, specific ECs, demographics, geography, personal story etc. can be used to evaluate an applicant for each school), the quality of interviewed applicants is almost uniformly strong (with the exceptions mentioned earlier), so that it's a (mighty frustrating) mystery how postinterview decisions are made. It seems to me that adcoms might as well throw darts at a board with interviewee names, it wouldn't make a difference: schools would still get strong classes because they already selected strong applicants to interview, and to applicants admissions decisions would seem just as random as they do now. In a way, I sympathize with adcoms: how do you really choose among so many strong applicants? - but I sympathize even more with my own strong application, decent interviews and lackluster postinterview results. Considering how many strong applicants there are to each school, at this point I realize that whichever medical school(s) will ultimately accept me will have more to do with luck than with my personal achievements.