The core issue is like you said - responsibility.

My previous employer ran an experiment. They had us come in two days per week for six weeks and ran the numbers. We ended up going 100% wfh with a downsized office. We been planning to double our office capacity before the pan.

I’m convinced that more than half of orgs would see similar numbers if they cared to look. I bet a bunch of the ones mandating RTO see them but do it anyway.