By that definition it is not stealing to take something that is unguarded, isn't locked or surrounded by a fence from a neighbors lawn, or a department store.

No, it's not. It's more like if Coca-cola accidentally published their recipe in the newspaper instead of an ad - that's their blunder and not corporate espionage.

No its not.

First of, there is also in legal a huge difference between publishing your secret in an ad and putting some .git folder in /.

Second it would probably still be illegal to reproduce coca-cola original receipe. There is probably some (c) or similiar thing protecting it.

That's one of the best analogies I've heard. Thanks for that.

Sure, if they took away the source code. But they only looked at the source code. It's not illegal to look at something in a department store.