One thing no one has mentioned is the ready availability of answers to homework problems on the internet. For many of my students, doing their physics homework consists in typing in the question and writing down the answer (or cutting and pasting it if they go that route). Of course, this does not lead to better grades, since they don’t learn from these exercises, but it sure makes things easier than they were for us back in the day. It’s a demoralizing problem for the faculty to have to deal with.