By "easier to shirk while remote" do you simply mean that it'd be logistically easier for an employee to do it if they wanted, or that people are actually doing it more? I don't deny the first, but I think the second requires evidence I have not seen. Have you seen evidence, and by that I mean methodically gathered, rigorous evidence, not anecdotes?
And then the next thing you'd want to demonstrate is that shirking your work duties more at home is actually, in practice and on net, damaging for overall company productivity. I mean, it's entirely possible that enough people both work less, and get more done in a more conducive environment. For example, by working in intense, focused bursts, then fucking off for an hour, then coming back to work hard again. As opposed to being forced to sit at a desk in a cubicle all day, surfing the web, hating your life, and doing as little work as possible even though you are physically proximate to your manager. That's a testable thing. We can find that out, but to my knowledge no companies who are mandating RTO have gone to the effort.
Instead, they're going with what seems obvious to them.
Personally, I will deny the first. It's much easier logistically to slack off in office because you can use charisma and politics to your advantage. You can make yourself seem productive, while not actually being productive, much easier in an office environment. Just talk a lot, talk loudly, and talk confidently. Fake it till you make it. Also, if you just look smarter, like if you're tall, white, and a man, that helps.
If you're wondering, this is why managers often suck. The ability to perform well in office politics and your performance/understanding are pretty much completely orthogonal. Slackers get promoted all the time, because they're likable and you're not.
In a WFH environment you can't do this, so more emphasis is on your actual work. You can't swindle people with a pretty face and confident timbre. Or, at least, not anywhere close to the same extent.
And then the next thing you'd want to demonstrate is that shirking your work duties more at home is actually, in practice and on net, damaging for overall company productivity. I mean, it's entirely possible that enough people both work less, and get more done in a more conducive environment. For example, by working in intense, focused bursts, then fucking off for an hour, then coming back to work hard again. As opposed to being forced to sit at a desk in a cubicle all day, surfing the web, hating your life, and doing as little work as possible even though you are physically proximate to your manager. That's a testable thing. We can find that out, but to my knowledge no companies who are mandating RTO have gone to the effort.
Instead, they're going with what seems obvious to them.