One reason is that these subjects are excluded from high school and college curricula.  Classes directly pertaining to the above mentioned trades are simply absent from our schools.

In order for someone to enter one of these 'bottleneck' fields, they must receive specialized training at an entirely separate institution.  This places a huge economic burden on both the students who want to enter these fields, and the public who need these services.  The bottleneck acts to restrain free trade, and drives up the cost.  Students should have the freedom to choose their own curriculum, and this doesn't only apply to existing academic subjects and classes.  Just like the student who is interested in math and can learn math in the classroom, the student who wants to become an electrician should be able to learn about this trade through the public school system.

The bottleneck subjects would attract a great deal of interest from students.  The major problem is that they are difficult to teach, but there is a solution.  We could record televised (via satellite) presentations pertaining to the aforementioned trades, and show these programs using large screen projection monitors.  This would provide stimulating, entertaining sessions for the students, while requiring very little preparation on the part of the teachers.  Additionally, teachers could learn from the programs alongside their students.  In an age of 'McDonaldization' and efficiency, it seems utterly inefficient to prepare the same educational presentation a thousand times, when it could be done only once and digitally recorded.  The curriculum could alternate between videos and discussion groups.  The class could vote on which videos would be shown, and decide what portion of class time would be designated for discussion.

We often hear teachers complaining that they can't control their students.  The solution to this problem is to stop trying to control them.  Education should be an invitation, not an issue of force. The school should make every attempt to come to terms with each student.  If this is not possible, then it is better to allow the student to find his own solution, outside the classroom if necessary.  Using coercive force is damaging to both students and teachers.

If these programs are developed in the United States, they can be used in other countries at little or no cost.  Inefficiency in education is a worldwide concern.  With relevant, effective educational programs, less developed countries would prosper.  A major defect of the accreditation process in these areas - medicine, law, etc - is that it is based on written tests.  There are many competent, bright, and creative people who are not skillful test takers.  For example, someone may be a very capable and responsible tile layer, but not be able to pass the written exam to get his contractors license.  Someone else may be a poor tile layer, but a good test taker.  And guess which one gets their license, hires people to do the work for them, and pockets most of the money?  Our society must understand that test taking skills do not equal competence.  An alternative method of measuring competency would be oral exams and/or on-the-job evaluations.