I've absorbed more knowledge from some of my professors than most of my teachers. Luck of the draw, I guess.
Not everyone learns the same way. Some people can pick up everything they need from listening. Some people can pick it up from reading. Some people need to do something with the material.
Like I said, most professors really don't seem to care if anyone learns in their class or not, thus shifting the entire responsibility for learning away from the professor (the person getting paid to teach) to the student (the customer). When high school teachers do this, they're considered bad teachers and politicians run on platforms to "hold them accountable" in order to maske sure the students are learning. College professors are almost expected to do it this way.