I don’t think it’s hard to imagine that people work better together when they are in the same office. It’s also not hard to imagine people work harder when there’s more social control. From the perspective of the business owner, this makes total sense. Yes, some people work harder and better at home, but, in general WFH is net negative for a company I think.
If you trust your employees so little, why even bother employing them in the first place though? And for what it's worth, I'm equally capable of slacking both in-office and at home and I'm definitely not alone in that one, it's just that the slacking is more often in the form of socializing, eating snacks, taking toilet and smoke breaks etc.
We have a choice thankfully, so no one really slacks in person or remotely because surprise surprise, when you treat your employees like human beings and not cogs in the machine they're actually motivated to do good work, who'd'a thunk it?