Well I’ve never seen a news article about one, and I’d suspect it would be a fairly newsworthy story. I’ve never even seen a news story or an anecdote involving somebody being knocked off their bike by somebody registered disabled, and I’ve seen plenty of such stories.
I’m not implying it never happens, simply that the number of cyclists hit by such drivers is so low compared to those hit by people perfectly capable of riding a bike, that using them as a reason not to have compulsory cycle training for all those capable of doing it is nonsensical. In case there is any confusion I am NOT suggesting that drivers incapable of riding a bicycle wouldn’t be allowed behind the wheel if such a policy was introduced.