Because automated teaching like this would render 90% of teachers useless and unemployed. And the NEA wouldn’t like that.
A computer program is fully capable of teaching most subjects to a student without supervision.
Only people who grew up in closets without normal human interaction can really believe this.
get some fresh air. take a saturday morning and go fishing. Take that freaking iPod out of your ears and go to a coffee shop. Start a conversation with a human being -- a conversation whose end you don't know from the beginning with a being you cannot control.
It's called "living."