Most parents would say a good teacher is priceless and a poor one worthless. School managers can only say a teacher is worth what the national pay scale allows and their budget can afford. Governments usually pay the minimum required to put a teacher in front of every class.
So most would agree that the quality of the individual andor the forces of supply and demand are important. So why is it that teachers are paid at the same rate, irrespective of their quality or the difficulty of filling posts in a particular subject, school or locality?
These questions are germane as the Government launches education action zones which will be free to disregard national pay and conditions. Ministers want them to experiment with the advanced skills teacher grade. "Superteachers" will earn up to pound;40,000 a year - presumably enough to keep them in red capes and blue tights as befits their status.
Those who don't appreciate the worth of a good teacher might find it hard to swallow the idea of forty-grand-a-year teachers. It's time they accepted that the person to whom they entrust their child should be well rewarded. But why do teachers themselves reject this opportunity? It seems that they think it is divisive.
One can only applaud the altruism, if not the realism, of the argument that teaching is a team effort with no individual stars. As a school governor I helped draw up a new pay policy. The teacher-governors consulted their colleagues and said they wanted no element of merit pay which rewarded individual teachers. We accepted that and applauded their team unity.
Yet most years that same governing body moved the head and deputy up the pay spine in recognition of their excellence. I was not alone in feeling there was a discrepancy here.
The danger of opposing higher salaries for a few is that everyone gets stuck on too little. Objections to advanced skills teachers miss this point and fail to recognise the positive impact a higher upper salary level would have on the profession's image.
We might regret it, but people tend to value things according to their price. Pay some teachers the same as a GP or a bank manager, and the overall image of the profession will improve.
Of course, some argue the profession will only be respected when all its members are paid a better salary. Yet they must recognise that what is holding them back is the same thing that holds back nurses' pay: there are half a million of them. It is so much easier for governments to give a bigger pay rise to smaller groups of public-sector workers, such as senior civil servants and judges.
So a different tactic is needed to change the perception of what a teacher is worth. The advanced skills teacher could be the Trojan horse which gets inside the Treasury's fortifications.
As the public gets used to teachers on pound;40,000, so it will be easier for the unions to press for this status to be spread more widely. Rather than opposing "superteachers", the unions should press for company cars, too.
It could help teacher recruitment. Starting salaries for teaching are not far short of other comparable jobs for new graduates. It is at the top of the classroom grade that the gap yawns wide. When choosing a career, graduates are as interested in future earnings as starting salaries.
The advanced skills grade has also worried headteachers. Some think that instead of upgrading classroom teachers it will mean downgrading deputies and heads at smaller schools.
Those taking this view believe education action zones will herald "superheads" who will take charge of clusters of schools. The smaller schools in those clusters would no longer have a headteacher but a "lead teacher". These former managers would then become the advanced skills teachers.
I doubt whether this is really the Government's intention. But I recall some years ago being told by many primary headteachers that they regretted the changes turning them into non-teaching chief executives. Perhaps some would welcome a turning-back of the clock, particularly if they could do so without loss of pay.
So, in the spirit of experimentation that the action zones are all about, surely teachers have more to gain than to lose from setting aside national pay and conditions? The Government is not going to risk the success of its guinea-pig areas by worsening pay and conditions. And surely the unions could afford the small risk of setting aside national collective bargaining in areas where it is already hard to recruit staff?
Mike Baker is the BBC's education correspondent.