If I were an employer and have rented an office space, whether the space is full or empty or half empty, I'm still paying more or less the same. Yes, there are coworking spaces where I can pay per headcount, but it's much more expensive (because the problem is now passed to the operator).
That includes things like:
* office-quality furniture -- sit/stand desks, chairs, videoconference equipment
* computers, monitors, whatever you would provide for them at work
* subsidies for lunch and snacks if it's the norm in your locale (it is for lots of companies in Silicon Valley)
* adequate lighting
* decent bandwidth internet connection
* housing market rate cash for the employee to rent a space with 1 additional bedroom than what they previously had, that can be converted into a dedicated workspace
* some reasonable budget for art/decorations/plants/whatever in your dedicated workspace. basically stuff that you would normally have in a modern office
All of this would probably still add up to much, much less than they spend on employees at a real office. It's for the company's own good as well -- do you really want your employees working out of a noisy cramped bedroom with 4 other housemates and strapped for cash to buy only used IKEA furniture with missing screws and sit cramped between a bed and a tiny desk, or do you want your employee to be focused in a comfortable workspace and get work done?
Then the staff member can outfit their workspace as they see fit.