And this is a problem of guilt by association, perception, and risk. If some of these programs have activities for the students that the med schools dislike then there becomes a negative perception About these programs overall. Add to this the already widespread perception many of these are Volunteer tourism, And overall the social programs are pretty widespread negative perception. Since applying to medical school is as much as push in the positive aspects of your record it is also reducing risk in that record. The overseas activity here Is wholly under the prospective applicants control and therefore the risk can be reduced by not participating in the activity.
Historically mission trips have been about building schools/churches, assisting in education, water and sewage projects, and similar. I Have in your blanket statement for my advisees: If an overseas volunteering trip has any health or medical activities, You should avoid those trips. Only people with qualifications, such as nurses, ER techs, And similar who are working in that capacity, either with a well-known group in the field, or an ad hoc group particularly for crisis aftermath (war zone, hurricane, floods) should be on those sorts of trips