Well that opened a can of worms, didn't it?
For the record, I have worked in several settings and I've seen some appalling practice some of which warranted a complaint to Ofsted. I have exposed some of these practices on MN threads and made it clear that I believed them to be unacceptable and what action I had taken. I'm all for whistleblowers being supported but not people who try to justify poor practice.
I've also had to handle some very difficult parents who had unrealistic expectations of me or the room staff, akin to the example above of the parent wanting a child to be prevented from being exposed to germs and much worse. When this has happened, I have listened carefully to the reasons behind the request and then, if appropriate, explained clearly and firmly why I can't accommodate it and made sure there was understanding and acceptance on both sides. Sometimes the parent just needs to be heard to feel OK.
I don't consider an early nappy change to be an unreasonable request, especially if the child is generally picked up at a predictable time. If the nappy were soiled it would need to be changed to ensure the child's comfort and well-being and the same applies to a child who will end up in wet clothes if they are not changed at this time.
It is not reasonable, in fact I feel it is negligent, to insist that a child leaves your setting in a nappy that you know will leak before they arrive home, especially given the outside temperatures at the moment and the effect wearing wet clothes could have on a small child.
Busy rooms are not an excuse. Ratios are the same however many children are there.
Nappy changes are a valuable part of caring for children. They don't detract from the time practitioners spend with children because they are time spent with children. They are an important part of the daily routine and can be wonderful opportunities for a couple of minutes quality one to one interaction with a child. There are opportunities for communication, for enjoyable little rituals like sharing songs and rhymes and building relationships.
I would be very concerned about a nursery where the staff didn't have time to carry out one extra nappy change 2.5 hours after the last one.