There are several stunningly obvious problems with that little diatribe you quoted. Can you spot them?
You're kidding right?
1. Teaching is not babysitting (despite comparisons suggesting otherwise). Outside of preschool and kindergarten (or some very special ed), teachers to not do play time, or change diapers (day care facilities charge significantly more for non-potty trained kids btw), or engage in significant individual activities with the students.
2. Pay does not scale linearly with number of children even in a day care or babysitting setting. Why should it when teaching? A good day care facility (full time) might cost $600/month. That works out to $15/hour/child. Yet, amazingly, a day care with 10 children for every worker doesn't pay their workers $150/hour (or $300,000/year).
3. Costs for education include the entire staff and facilities, not just the teachers in the room. When you account for total faculty compared to total students, it's closer to 10-1 ratio, not 30-1. So we should just not pay the rest of the staff? And I suppose those buildings are free too, right?
4. I could probably come up with more, but I'm honestly dumbfounded that anyone questioned that this is an incredibly flawed comparison with silly-math being used to make a moronic point.