Here are a couple of thoughts from my perspective: Too much opacity in the brand-ownership model. Brands make the commitments with little or no teeth at the operational/ownership level. Owners can benefit from the halo effect of corporate announcements without (full, immediate, consistent) implementation.
As a sustainability consultant to the hotel industry, there is very slow movement toward sustainable hospitality. The major hotel brands that have set goals do so for the properties they own and manage, which is perhaps 10% of the hotel inventory world-wide.
The referenced ITP scenarios are based on the clear forecast that the hotel supply will grow immensely in the coming 2 decades. Sustainability needs to be addressed from the beginning of the hotel project, even before operator selection when initial feasibility is done and/or capital investment is decided.