A lot of people work worse and more error prone if they feel like someone is breathing down their neck.
Looking over shoulder != breathing down their neck.
Most people do need a bit of pressure to be at their most productive, that's pretty much the core of a procrastinator, which most people are to some extent.
Sure, there's people who maintain high productivity with no external pressure or close oversight but they're rare.
Agreed WFH is an over-all positive for both employer and employee.
This is the argument that bugs me. WFH is a positive for the employer in the sense that it reduces wages and real estate costs to some extent, but I think the productivity cost is real and negative for some employers.
This claim that WFH is clearly a positive for employers (and explain away all the employers against it as somehow corrupted/delusional) just feels like an attempt to dodge the fact that it's a trade-off.
Let me frame it another way. I think we can both agree that chattel slavery was a very bad thing and it's a good thing it was banned (in most of the planet).
However, it was probably in the economic interest of slave owners for it to continue.
The argument against slavery isn't "oh, it was bad for the slave owners and the slave so everyone will be happy when it's gone". The argument is "even if it was good for the slave owners it was horrific for the slaves and the cost to the slave owners from abolition is nothing compared to the benefit of the now freed slaves".
Not to say that working in an office is remotely comparable to slavery, just that for something to be a good thing doesn't mean every single party involved has to like it.