I think there's probably a couple of things that are getting confused here:

1) Big pitched battles were RARE. Even the best generals only fought one or two. Perhaps that's why they were the best. Far too much is at stake. You could lose everything in one swoop. Therefore actual big, organised charges wouldn't have happened often.

2) The quality of the opposing troops. Knights were soldiers (essentially, trained from childhood etc), equipped with the best equipment, and keen to show off their bravery to their peers. They might be charging untrained peasants, armed with a stick. Of course they are going to win. But maybe not against a motivated and trained block of well equipped men on foot. Probably not in fact. How many cavalry charges worked against well equipped, trained and positioned pikemen?