You sound very bitter, which may have some basis in circumstance. All the same, degree certificates may be written on 'bits of paper' but they represent a lot of work from the students (as you will know as you now have one yourself), and it is very unfair to dismiss them in this way. It is a brave step to go to university later in life, but often people find that the rewards are worth it.
If, as I suspect, the degrees are validated by a professional organisation, they will have to meet the standards laid down by that organisation, and the universities who offer them are regularly visited to ensure that they are kept up to date with developments in the profession. New graduates will be inexperienced, as are all new starters in any workplace, but they will have much more recent knowledge and other transferable skills.
I can't comment on schoolteaching from personal knowledge, but my understanding is that a training college course was for primary teachers, where they don't need expertise in a particular subject, but an understanding of how small children learn a wide range of subjects. Secondary school teachers have needed a graduate level subject specialism for a long time, AFAIK.