I’ve spent a lot of time with windows and probably not enough with doors. I’ve closed a lot of them, knocked on some and left without waiting long for an answer, walked past them and assumed they’re locked.
I think, with windows, I can see what’s on the other side without opening them, in case it’s cold or raining or the wind is blowing hard. And I can sit in comfort knowing that I’m not actually exposed.
But in all my years working with glass, I’ve learned that no matter how clean you think it is, it’s never completely clear.