I think that some of what's at play is that, with an undergraduate degree, engineering and tech are the only STEM majors that give a good chance of actually working in STEM. So you even a majority of STEM degrees may not lead to a majority of STEM workers.
For what it's worth, I also don't think that most people would consider psychology or social science to be STEM and this is the first time I've heard of STEMM to include "medicine". So that may factor in as well.
For what it's worth, I also don't think that most people would consider psychology or social science to be STEM and this is the first time I've heard of STEMM to include "medicine". So that may factor in as well.