Not steered away, but I think that it would be helpful for guidance counselors or college academic advisors or parents to point out that engineering or medicine is a particularly difficult path and one that may be quite different from what the student expects.
Then, it might make sense to ask ALL students who are aiming themselves in these directions – not just the apparently underqualified – what they might like to do instead if they find that engineering or pre-med doesn’t work out for them or that they simply don’t like it. The answers could help the student choose an appropriate college and program.
The prospective pre-med who says “If pre-med doesn’t work out for me, I’d like some other job in health care. I’ve always wanted to work in health care in some way” might need to be in a different place than the one who says “If I can’t be a doctor, I want to major in business.” The prospective engineer whose alternate major is economics might need to plan a different freshman program than the one who would like to be a biology teacher if engineering doesn’t work out.
Lots of people need a plan B.