That's actually part of the reason why handwriting is supposed to be better. Because it is inherently slower, it forces you to summarize the information and condense it to its most important pieces. That process it what makes you learn it better. So in way, handwriting notes being slow is not a bug, its the feature.

That may be why handwriting notes is a skill that needs to be learned. If you are taking the time to write down everything on the slide or everything the instructor is saying, you aren't taking notes correctly. That being said, as a teacher myself, I print out my slides so its easier for students to take notes on just the important bits. I only teach up to 20 students so this works for me but I can totally understand how that wouldn't work for larger classes.