Makes sense. Probably one reason most of us get into this is that we love bio.Someone more knowledgeable please correct me if I'm wrong, but I think it's got to do with the MCAT subsections being scaled but not normalized. If the distribution of raw percentages correct is different between sections, then the scaled values will be at different percentiles.
I once plotted the percent correct vs percentile for the old test, and it came out showing Bio tended to have higher raw percentages correct. So yeah, in a sense, people do better on Bio.