Do you think everybody is truly, sincerely making their best to make it to class on time? Or some people just don't think is a big deal being a few minutes late?
I think regardless of the subject you're taking, if you're actualy interested in it you're going to do your best not to miss any of it.
I also think that not everyone studying a subjet is there cause they really want to be or there as more than a causual interest/curiosity. Those folks I think probalby dont make as sincer an effort not to miss out on anything.