University courses differ. In some third-quarter calculus courses, there's a lot of differential equations. In others, as you point out, some multivariable. In others, an introduction to linear algebra.
It seems to me it's up to the individual university to decide how much credit to give, and which courses to exempt students from, after they've had BC calculus. And the BC curriculum should try to represent some kind of average, which I think it does a fairly good job of doing.
To get up on my personal soapbox, I'd rather see the BC curriculum "rather than cover many topics, uncover a few" but the colleges need to lead the way on that one, I think. Us high school teachers won't have the clout, until college calc courses start working with fewer topics in more depth.