If a kid is impressionable, they are likely that way in all aspects of their life, and it would be my hope that the parents have addressed that issue during childhood, in order to avoid unpleasant consequences that might arise not only from fraternity interactions but any general interaction with “the wrong type of person” whether it be at a college party, a dorm, a classroom or a job.
Speaking to my experience with sororities, there are many independent thinkers and leaders who seek out the opportunity to join these organizations, not only for the social connections to similarly strong women, but also for the networking and alumni connections that these groups provide.
Certainly, if a kid feels some kind of peer pressure by the mere existence of Greek organizations on a campus, they should seek out colleges where Greek organizations are minimal or non-existent - however, there are thousands of students who successfully co-exist on campuses of all sizes, where Greek life is present. They simply make the decision not to be associated with it and move on with their college life.
I don’t doubt that there may be some small campuses with a large Greek presence, where a kid may feel like there aren’t opportunities to be social unless they go Greek, but that’s why it’s important to vet the campus culture before depositing and make sure it supports your kid’s social personality type.