Dogs are strange people.
Most of them actually seem to enjoy doing things along with their human companions. I have seen videos of the dogs joining in a Congo Line, with their paws on the back of the child ahead of them, and tail wagging, as they went along with the line. We see dogs playing the piano, riding on horses or ponies, going down the slide at the playground, and all kinds of non-doggy fun and games.
I had a little white Poodle and I sometimes bathed her and added cherry kool-aid to the final rinse, turning Miss Betty into a stunning Pink Poodle.
She knew that she would get extra attention and petting from people, and this little dog just loved it ! She would be extra outgoing after she was groomed, and looking for someone to pet and cuddle her.
I agree that some of these dogs in the OP must take hours of standing to be groomed, but the dogs in the picture seem to look happy and like they are enjoying all of the attention.
I think it is more like dressing your child in that perfect Halloween costume than it is the beauty pageant. The show dogs that have to live a "groomed for show" life are (to me) more of the comparison to the beauty pageant girls.