There are some very dubious comments on here.
I was teaching when the first training days, (Baker Days ) were introduced, and although some training sessions were better than others,and we had many, I never knew anyone in any school I worked in have the day off to go shopping. TAs were expected to attend as well, if they dealt with whole school initiatives such as safe-guarding or introduction of new reading, maths schemes etc.
They are not a money making scam, Gillybob; the fines were introduced in an attempt to prevent children missing vital time in school, however little you may value it, and they improved attendance and results. It is difficult to make up work children have missed, particularly when there were so many different absences at different times.
The trouble with using discretion is that it sets a precedent, then the Head has to defend each and every decision.
I am shocked by some ex-teaching colleagues who complained bitterly about children missing school for holidays, who now bombard Heads with pseudo educational -speak about why their grandchildren should have time off, or stupidly pay the fines themselves.