So for example, if you've got 500 people (customers) walking through your building plus 200 people (employees) doing things, then the restaurants and shipping stores and etc can estimate some % of those feet turning into sales.
But if you've got only 300 people (customers) walking through your building plus 50 people (employees) doing things, that % of feet turning into sales goes waaaaaay down. And your retail outlets in the building end up with far fewer sales. They either go out of business or demand cheaper rent.
That's just one way of estimating commercial real estate.
Let's figure your attached parking garage. Assuming it's not-free, then all those employees not paying their parking dues ends up causing the parking garage to not generate revenue. Ooof. Or, let's say it's "free". Well, the people who reserved spots paid for those spots whether they use them or not. But the people who don't reserve spots? The business isn't seeing a return on investment if their employees aren't using them, so why pay their share for maintenance of that parking garage?
What about the HVAC and plumbing? The building owner's son owns those businesses, and it's pretty damn expensive to keep HVAC and plumbing working at peak efficiency. It becomes a lot easier to do if they're not used as much! But your son's business is going to get churned if you don't pay them less for the decreased maintenance costs. And you can't just stop maintenance because those things get damned expensive when they're unmaintained.
And the shipping staff? Well they have to come to the office anyway otherwise nothing gets shipped. It's not fair to those staff! You pay them complete shit, and they used to be able to eat lunch at a decent restaurant and have a decent place to park and have good air conditioning and working toilet. But now, with just everyone else being out of office, the restaurant went out of business and the HVAC is set to a wider range of climate and the toilet's been clogged for a while.
Instead of paying the shipping staff something reasonable to offset their changes, or changing the way that lunch and support services are handled... just demand everyone else come to the office too. That's cheaper.
Nobody would hurt labor productivity to save an office. It’s backward
It's entirely possible that the question of "labor productivity" has nothing to do with why exec wants us all back in the bullpen, where they can gleefully stare at us from inside their offices.
