It is possible that horses will not charge if they were poorly trained, but I don't think this was common. In fact, Polish winged hussars (who are really just knights of course) apparently charged even pikemen and were often victorious. It is worth mentioning that their lances are actually longer than pikes though.
I think you're making a mistake equating the Polish winged hussars with typical western knights.
First, their heyday was in the early days of gunpowder, when their enemies were musketeers guarded by a smaller number of pikemen (who did not have shields).
Second, they were a truly elite unit,
literally awesome, with, as you mentioned a special hollowed-out lance that was significantly longer than the pikes they faced. (They also used an enormous thrusting sword, once their lance broke. And pistols.)
There are good reasons why medieval warfare was dominated by mounted knights. Imagine a tight line of long lances moving against you with great speed and enough momentum to propel you a few dozen yards, punching through armor and most shields.
I think you misunderstand the point being made. No one is claiming that knights are
inferior fighters, just that a cavalry charge relies on a break in the formation of the defenders. This break might already exist, or it might form when the defenders lose heart and begin to flee.
And, as you recognize, a charging line of winged hussars should send most troops running.
This is precisely the reason why spear and shield, shield walls etc. became obsolete. They never fell completely out of use in middle ages since horses are not always available or practical, but medieval battle manuals knew better than throwing them against knights.
You can't "throw" footmen at mounted knights. Mounted knights are mobile and only engage when and where they want to -- and a moving formation of infantry has trouble maintaining a perfect "hedge" of spears against cavalry without revealing a gap.
If you look into medieval knightly psyche you will see a lot of emphasis on courage and boldness to the point of overconfidence. You need some if your job is to charge enemy ranks without flinching. If knights cannot charge, they are already defeated.
The charge is a game of chicken; whoever flinches first loses. If the pikemen are professional and don't run at the sight of charging knights, they can hold their ground. If they lose their composure, they get run down.
(I found an article on
How the Hussars Fought, for anyone interested.)