Compulsory check-up would be implication!

Insurance companies would see you as "reduced" risk. That is why they offer lower premiums for ladies (not as reckless as us fellas - allegedly - but they have not been on a track day with the wife and her pals

) As IAM/RoSPA member - insurance cost is reduced as "supposed to be responsible and safe chap and less of an accident risk"
You have to have some give and take - if the numpties out there see a return for outlay of a driving course fee, they would perhaps be more willing to accept it! If you force them to shell out more money - even if the return is their safety on the road - they would balk at it!
After all - insurance can go up if you have 3 points on licence as you are increased accident risk in their eyes - though there are some indications that more and more are not penalising for 3 points on grounds that so many have them now!
But reason for saying "brush-up" or similar is that people would "gag" at idea of doing that TEST

again! Formal re-test should be only if chap is complete numpty behind the wheel and this is only course forward short of life long ban!
Personally - would encourage all to at least think of IAM or buy some of the publications for tips on safety and control! Not as good as actual practice - but good to know theory behind it!
Two of the youngsters in our family have IAM already. Aged 19 & 20 -very useful for parental peace of mind,

road safety, know-how and awareness, as well as "useful" for insurance. 17 year old just completed Pass Plus and will be looking at IAM when more experienced. Their parents say they still had to shop around insurance-wise for reasonable "deals" for young drivers.
Their experience (three different family units): IAM youngsters - received reasonable (but not great) discounts presumably again due to age, but the youngest one's parents found that some insurance companies offered no discount for Pass Plus - which was astonishing! He is not even driving a flash car! A Corsa!
Has any one else experienced this with Pass Plus and insurance? Do know of 2 chaps on another forum had this with their lads and lasses!
If this is case - could be why apparent slow take-up of Pass Plus? (Seem to recall something the wife showed me on this - have to look it up!)