"I wonder what some of these artists get from putting their name to what is ostensibly someone else's work. Apart from vast sums of money, obviously."
It's not someone else's work. They designed the art, they came up with the idea.
Can a builder/fabricator say that the building is their work, not the architects?
Can a seamstress say that the clothes are her work, not Stella McCartney's?
Can a conductor say that they concerto is his. not Beethoven's
Why do you think that artist's have to do everything themselves? Art is about concept and idea as much as it is about labour or skill. This is really not unusual or controversial.
Why is this such a pernicious concept, that artists should be painting every mark?
and also, why is it considered weird/bad that artists can be rich and benefit financially from their creativity?
The "starving artist genius in a garret who doesn't make any money till they die" stereotype is so popular and pernicious that it seems to colour popular views of what artists are/ should be. It's not, and has never been the whole, or even a fraction of the truth. There are MANY MANY different kinds of artist.