None of us actually know the reason doctors are excluded - it may indeed be that some are too busy as jobloggs suggests, or poor handwriting as Farmberg suggests

It would be interesting - but expensive - to put this to the test, and actually sign one of these documents

Meantime if I do find out the reason for our exclusion I will post again on this thread.
Here's another suggestion, which I mean sincerely. Dedworth has a "way with words" when dealing with authorities. It could be helpful, if he was willing, to write requesting the reason for excluding doctors from these lists.
This is not so much hurt pride at our exclusion - I'm not that sensitive ! - but doctors would seem often to be most accessible professionals to ask in these circumstances.