I think your son is in excellent shape for the LACs (with addition of some safer schools of course) on his list if he and the colleges he likes are a good fit for each other. I do agree with the “it” factor mentioned upstream, and what “it” is varies among LACs. There are a certain number of applicants who will get into most/any of those top LACs- truly exceptional candidates- and then there are the more typical “excellent” 17 year old applicants who produce the academic transcript necessary to make the cut and who show (via their essays/ECs/recs) an intangible side that appeals to adcoms. This is the “it” that gives the adcoms an idea of what that applicant will do once on their their campus, what that student will bring/contribute to campus culture, how that applicant will help shape community.
When it comes to LAC admissions I do not think it is a lottery type admissions crapshoot. Could be for HYPS types (don’t know a thing about their admissions), but not for the LACs. Even the tippy top LACs put a ton of thought into applicants that make the academic cut, and they rely on the “it” to push the kid from one pile to another. They aren’t looking for perfectly finished 18 year old machines, they are looking for students with the potential to benefit from 4 years at their institution and for kids whom their institution will benefit from during those 4 years.
The nice thing about this college process is that the applicants can learn so much about themselves. Visiting schools- eliminating and adding choices- helps define the type of community that interests them. The essays allow them to do some serious soul searching, they push them to reflect upon what makes them “tick” so to speak. Listing ECs helps them define their “story”, helps them present their interests in a way that can/should tie academic interests with personal interests. In the end it is a long process for most kids but so worth the effort. And your son will do very will admissions wise if he chooses schools that are a good (mutual) fit. He doesn’t need a ton of schools on his list, just enough reach/match/safe schools to feel confident he can be happy whatever the outcome.