Some people hate cleaning and tidying and are happy with the way their house looks. As Quentin Crisp said (and I paraphrase) "After three years the dirt doesn't get any worse. You just have to HOLD YOUR NERVE"
Lots of people hate tidying but want their home to be tidy. They need to get better theories, either about to what extent cleanliness matters, or about whether it is fun to clean or not. I don't think it really matters which route they follow, but if they have decided to be tidy then:
Get lots of stackable plastic crates. Or handwoven organic sea grass ones if that's your preferred asthetic. The plastic ones cost almost nothing, though. They are great for having toys sorted into - lego in one, soft toys in another, musical instruments in another. They are also excellent for building dens, for impromptu tables, for climbing onto large items of furniture...
People with a competitive streak can turn tidying into a competition, with their co-habitees or against themselves. e.g. throwing plastic balls into a filing cabinet drawer from the other side of the room = target practice. Child might want to join in while parents are having fun with such a game - no need for nagging. And if parents are having fun, they won't actually mind if child joins in or not.
I think of tidying as re-setting the house so that all the toys are attractive to whoever might want to play with them - making sure all the jigsaws have all their pieces with them etc. Any toy in its home is a gift to my cohabitees.
Someone said to me that if there are items you move in tidying more than once every 24 hours, then they live in the wrong place. It may be that the home of a very favourite toy is in the corner on the floor, not up on a shelf.