Just saw the end of The Queen. If accurate the applause seemed to be for her brother, Earl Spencer's, tribute speech at first. Later it was, as the hearse passed, to applaud Diana and her achievements I guess.
Since men no longer routinely doff headgear I think it shows respect, better than trying to pretend someone's last journey just isn't happening.
I remember the Russians applauding at political events when we wouldn't have done in the 196s., Krushcev et al I think.
I've intensely disapproved of game show contestant clapping themselves but just sometimes it can seem that they are thanking the studio audience or 'clapping back' their opponents.
Trump marching on stage clapping himself looks brash, gross, offensive. I keep wondering what 10 year old Barron is making of it all!
PS Not are all keen on whooping!!