Gertrude,
You will have read Sir George's comments that airfield operators can set what conditions they like, such as to wear top hats or clown outfits, or even 'hi-vis jackets', and a judicial review would undoubtably uphold this. Your point is irrelevant.
The posts made show that this is an absurd requirement from any rational analysis, and thankfully, most small airfields do not have the requirement. If true, it would dismay me if Tollerton, into which I have flown many times, now wants it, especially as whenever I've been there, aircraft parking is right alongside the fence adjacent to the cluhouse.
I see that you are from Cambridge. It so happened that I flew into Cambridge recently, the first time for over 30 years. It is the only airport I have ever visited which has Hi-Vis J's on pegs by the airside door which could provide the facility required by your earlier post. And if I brought in a PA32 to pick up 4 passengers, would they all pick up jackets to leave at the farm strip where we are going? (and not coming back to Cambridge) Some airports at least have the sense to limit the requirement to aircrew.
I did finally succumb and buy one a couple of years age (£1.49 from a web site), up till then I had got away with a yellow polo shirt from Trimark. The requirement remains an absolute curse, except as Sir George says, one can avoid airfields with the requirement. I find that some who nominally have it, and want to encourage visitors, make no attempt to enforce it, so I can leave it in the aircraft.
The reason its a curse is that 90% of my flying is to other airfields where I am just not prepared to carry anything when I go to have a walk, lunch, or whatever. What do you do with the damn thing - I know, put it on a hook where it certainly wont still be when I come back to fly home a few hours later!