Isn’t the answer here if you can’t get someone with keys in a reasonable amount of time to break a window? Most doors have windows adjacent to them, and the company can just call the security people and tell them it’s part of DR.
Any secured area isn’t going to have easily broken windows, but there’s also no such thing as an intrusion proof building. Ultimately the main point of any security system is to slow down an attacker before people with guns show up and pointedly ask you to stop doing that. If it’s your building, you can use a blowtorch to get in if you need to, it just won’t be as fast as say, breaking into a residential home.
My company is not Facebook, but in our data center there are no windows and the doors and walls in specific areas are designed to hold off physical attacks.
