Outside of the current crisis I think this holds true doesn't it? I'd be curious to compare how many employees AirBnb has per bedroom compared to a hotel chain (and then factor in that they are still in the process of scaling).
The issue now means they have pretty much zero revenue, but that's kind of beside the point. I'd venture to guess they can manage costs better than a hotel since they don't actually own any buildings, or employ the folks that maintain those buildings. As far as property costs, they take a one time hit on cancellations.
Underestimating employee counts is a phenomenon similar to underestimating software rewrite costs/time. The happy path seems simple... but then there's thousands of marginal features or requirements that have come up over the years that make the thing more viable that all take more people and more time.
Marriot et al employ hotel staff, cleaners, chefs, restaurant staff, bar staff... people to run a hospitality business.
Fairer comparison would be booking.com with 17000 people. Which still seems quite high to be honest.
I mean at what point will people stop valuing a business like that like a tech company and start valuing it like a rental company? Because the defining feature of technology is essentially low marginal cost at scale, and these companies just seem to keep growing in their human labour.
This seems generally true for a lot of companies in the "sharing economy" space.