If a school's matriculating gpa is low it doesn't necessarily mean that their standards are low - it merely means that the students that accepted their offers of acceptance had low gpa's. It's very possible that Howard and Meharry routinely have applicants that have great stats but simply decide they will go elsewhere for whatever reasons. And I wouldn't correlate numbers at a school to degree of ease.
I don't know if students have a harder time with the material at those schools or not or what their drop-out rates are. In my opinion a student's success is determined in a large part to individual work/study ethics and time management versus the vibe or 'aura' associated with a particular school.