'shoes off' is an American invention. It is not required in the UK although they do ask for 'boots off' and advise that larger or bulky shoes may need to be removed.

I have never myself removed my shoes nor seen anyone else had to remove theirs unless boots (or if the Americans on queue did it without being asked)

And there are reports on the family board of TSA denying forumla as 'not needed on the voyage'. TSA has the medical training to determine if a parent is bringing too much formula on board for the length of journey.

Somehow I don't think that a TSA experience would necessarily have been better.