Why on earth would you NOT have nets or something in the window?
Quite honestly i'd be embarrassed to have someone look in, not angry. I'd worry they're judging my home, how clean it is or isn't, if i look presentable or not (probably not, my hair wouldn't be done if im not going out somewhere).
I guess i kind of just naturally assume people who don't have them are kind of exhibitionists who either don't care about being watched or who maybe even get a kick out of it.
Then again, as a very young child (6 at most) i was playing out in the street of a friend, and happened to lean face first against someones window (i think i was counting for hide and seek) the gentleman inside got VERY angry and shouted at me (couldn't hear him but he was looking at me and was clear he was angry at me looking in, even though it wasn't something i did intentionally) but it was late, it was getting dark, and his curtains weren't closed. I can still picture the layout, where he was sat, the child in the nappy next to him, and this was at least 20 years ago. I remember the sheer panic i felt, that i had done something wrong, something bad, and genuinely afraid he was going to come out of the house you shout at me or worse.
If you don't want people looking in, put up a barrier, and close your curtains when it starts to get dark and people can see everything because the lights are on, even from across the street!