I'm an Aspie. I don't normally strike up any conversation with a stranger unless it's usually necessary for some reason.
To do otherwise would never occur to me to initially compliment them in the process.
I see a little irony and humor here. Perhaps it comes from seeing one too many "Leave It To Beaver" episodes where Eddie Haskell is complimenting someone always for a reason other than simple flattery. It spooks me to an extent, somewhat like eye contact.
I'm very self-conscious about maintaining a sense of honesty given a lifetime of social anxiety. An unsolicited compliment to a complete stranger just wouldn't be comfortable to me. I guess on some levels we really do exist in a very different place in our heads.
How would I strike up a conversation with a total stranger? Short answer: I wouldn't.