I don't think it's fair to say they don't care - they obviously do, you can tell that from how they have repaired theming across the parks over the past few years, obvlion had a repaint just a couple years ago Nemeis this year.
What they don't have are the budgets to spend multi millions on referbs.
I think Merlin do a better job at up-keep than we had under Tussauds.