They're at work, they're supposed to be suffering from eye strain. Desks facing walls is bad, because you can't shift your view to something distant to rest your eyes without turning around. And I wouldn't even dream of working anywhere that had the mentality "you should be working all the time so it doesn't matter who is looking over your shoulder". If I need to spend 5 minutes talking to the wife on IM, I am going to. If you have a problem with that, you're going to have a hard time hiring good people.

They are professionals--they're supposed to be delivering value for the company. If watching netflix helps them think, let them watch some goddamn netflix. Butts-in-seats is a horrible metric; butts-in-seats-with-code-editor focused even moreso.

I hate people sneaking up behind me while I'm wearing headphones. Plus, some information is confidential even within a company (eg if an employee has an HR concern like feeling upset about another employee).