Sorry I haven't received my scores yet (June tester) but hopefully I will be able to answer it when I recieve my scores 🙂
I think one big reason a lot of people on the new test are surprised to see those 131s and 132s is because they are still equating them to 14's and 15's. On the old test, you would pretty much have to get every question right for a 15 and miss 2 tops for a 14. Also only ~2% of people got a 14 or 15 on the old test per section (except VR ~1%). Now it looks like 3% of people get a 131 or 132 across all sections, including CARS. So one could say its slightly easier to score that high in a section.
Luck, of course also plays into it. Out of all the people on the old test who made 15's on a section, some of them may have had to guess on like 2 questions and just happened to get them both right. I got 5/6 right once on a CARS passage in one of my practice FL's that I had to guess on because I was running out of time. The MCAT mixes a lot of easy and medium difficulty questions with some hard ones, and 1 or 2 questions that are super hard that separate the 14's from the 15's. When testing a bunch of very smart hopeful doctors, they design a test that sets a stratification to ultimately weed people out. That is ultimately what the MCAT is for and is pretty much the purpose of many standardized "admissions" tests.