Tho only windows in my quonset garage are two small ones on the walk in door,none anywhere else,or in the overhead door--I used 2 of those "glass blocks" in custom frames on my home made walk in door...no one can see anything thru them from the outside--looking out from inside,everything is distored,like a bad acid trip--but you can "see" any intruders and vehicles if you look in the right spot...
I ended up making "shades" for them on the inside,so at night,no one going by can see the lights on in the garage too...
I do not enjoy needing to have lights on constantly while inside the garage ,unless I open the overhead door,but I'd rather pay a few bucks more for electricity than to give thieves an open view of its contents.
I tend to keep the doors closed unless its very hot out for that reason too--I find leaving a door open seems to encourage someone to stop in if they are driving by,or a neighbor wants to chat,etc,like its an open invitation,often that interruption will derail your progress on a project or worse,make you f*** up something ,trying to talk to someone who's being a hinderance rather than a help,you know ?..Unless I need a hand,I dont want an audience !..
Also I have a hard time thinking something through or concentrating when outdoor noises from neighbors,barking dogs,screaming banshee brats in pools nearby,sirens,etc-- so the doors stay shut as much as possible--it also keeps the loud music I play to drown out such annoyances, and occasional air tool use from being an irritant to my neighbors..even though by rights I shouldn't give a crap about them--they have no consideration for anyone else but themselves..