Whilst I see your point, it is not really a valid comparison. I would be much happier learning from an untrained teacher than receiving surgery from an untrained doctor. Maybe a better comparison would be a lawyer, although I guess retaining a bad lawyer could get you locked up. Not that I am in any way saying that untrained teachers are beneficial, it is a shame that children cannot receive the highest level of education possible, especially as it will often be down to a lack of funds.