Office space is almost never an advantage. There is virtually never any marginal savings, ie they have room for you in the office, you just don't use it. And offices aren't that expensive relative to salary anyway. Even sf office rents are $70/ft2. I see your point if you go remote-only, but that really isn't what we're discussing.

Price for a week in the office in sf: $500-ish flight, 4 hotel nights $1100, $90 per diem $450, taxis/ubers $30/day = $2k - $2.5k. Throw in a $500 team lunch or two.

I agree remote workers can be more productive; I certainly was. However, I used most of those productivity gains to work fewer hours.

Cost is tricky because the big costs are a step function.

So long as there's an empty seat in the office, it really doesn't cost much to have someone sit there every day. Yeah, there are some free drinks but it's really in the noise and might well be dwarfed by some additional travel for the remotee to come into the office now and then.

However, at some point, having a significant number of remote workers may mean you don't take out a lease on an additional floor or move to a bigger building or construct a new campus, which can be huge costs.

The productivity debate has been done to death and I won't repeat it here :-)

This is only true if a large % of your employees are remote. Making exceptions for a few has no upside to hard costs.

EDIT: And from my experience, 30% of people work more productively remote, 40% about the same, 30% are less productive. That said, there are also productivity losses to in-office people when a smaller percentage work remote, especially if their jobs require frequent team interactions.

For developers it is certainly doable. For other teams it takes a lot of effort for everything to even out. Some companies have figured it out, some have not.