Airport properties are a weird niche because the majority of their stays tend to be a single night where a non-airport property will tend to have greater proportion of multi-night stays so this observation might not be entirely accurate but: In a pre-covid world where both stay overs (e.g. not checking out) and check outs/turns got daily attention, now not only do you have a dramatically reduced number of housekeeping attendants (I've stayed at a few--albeit no more than 150-200 key--where the entire housekeeping department would appear to be 1 housekeeper + the night auditor doing laundry ) but they are essentially only turning over rooms which takes more time per room to accomplish... and with the constraint of having a majority of those rooms ready by check-in...

Of course on a lightly booked property letting those rooms roll as vacant-dirty to the next day may be an option but eventually those rooms will need to be turned. I don't begrudge a property that turns me down or doesn't give me as long as I like; I appreciate when the courtesy is extended -- and more often than not it is (though I've found asking in person to be more successful than calling... and sometimes the answer changes when they notice my status... but if I really want ("need") a late checkout I just book the room for the extra night.