The only answer I've heard across the internet is "because CEOs want to harass/micromanage their employees," but that sounds like an immature internet answer. Having employees return to work sounds economically counterintuitive. The company has to pay for electricity, maintenance, basic necessities (coffee, toilet paper, pens, pencils, yada yada...), it creates more traffic on the road, it increases possible work-related accidents (slips/falls, etc), and on a cultural note, just makes people's lives more "ugh, I gotta get up early and sit at a desk for 8 hours."

So what are the economic benefits of returning to physical-location work?