@Jacinta49 "It's highly unlikely the cleaner will be booked for a sunday afternoon, for example. "
What??? Plenty of hosts take back to back bookings and of course their cleaners come on a Sunday if that is when guests are checking out and new guests checking in.
Not all hosts leave a days prep time hetween bookings, in fact I woukd venture a guess that most hosts don't. One person checks out by 10 or 11 am, the place gets cleaned and restocked, and the next guest checks in after 3pm.
Personally I do leave a day's prep time between bookings, so my check in window is 11am-11pm and check out by 4pm. But that is the exception in Airbnb world, not the norm.
What you are referring to as "rigid" is a matter of losing a night's booking fees. Few hosts who are striving for full occupancy are willing to give up anywhere from $50- $1000 just to accommodate guests who want to check in early and check out late.