Actually, what was said about medical school admissions is correct. The number of UK medical graduates each year does, in theory, correspond to the number of F1 placements available in the UK as a whole. Medical schools are only provided with funding for this number of students, which is advised upon by the GMC. If a medical school goes over its supposed quota, it's generally down to there having been an excess of (lucrative) foreign students admitted, for whom they won't receive UK funding. Anyone can apply, of course, but they can't all get in. This frequently leaves a number of high school leavers with, on paper, the 'correct' results not gaining a place at a medical school. If there was no relationship to the number of F1 places available, you'd end up with hundreds of doctors with no route to GMC registration, preventing them working either in the UK or elsewhere.
The numbers studying law aren't related to any kind of quota, but there are a ton of law students and graduates who have no intention of ever being a lawyer. The same can't be said for medicine.
I'm saying this from the perspective of having gone to medical school in the UK.
Pilot training, at least non-sponsored, doesn't bear any relationship with the potential number of jobs, as everyone knows.