Defecating in the street, it's just not cool to do it anymore.  Oh sure, you say.  Taking a dump on the sidewalk or in an alleyway went out of fashion in the early 1600’s.  Everyone knows that!  Not that the practice was ever fashionable, per se, but it wasn’t entirely uncommon in the 1500's.

Dysentery doesn't make itself folks!

There isn’t much standing between you and a turd on the sidewalk right now even. Primarily the voices running through your head keep the crap out of the streets.  Get rid of that internal monologue and you're two minutes away from stepping in human feces on a regular basis.  It really isn't much different than robbing a liquor store at twelve o’clock in the morning.  The primary obstacle, many people face, is the build up to the action.  Before anyone even walks through a door generally the mind escalates the situation internally with anxiety of the unknown.

“What if I get caught?" 

"What will everyone think of me?”

"What will everyone do?"

"What if the owner has a shotgun?"

I’ve never robbed a place before, but I've thought about it.  Robbing a liquor store (in and of itself) cannot really be too difficult a task.  Keep a firm grip and solid aim.  Use loud, commanding tones. 

Generally, people can be kept in line long enough to receive two hundred dollars cash.

What stops the thought from becoming reality?  Anxiety.  Whether the thought is of: robbing a liquor store or pooping in public—the internal censor says, 'That's just not right.'

Which would you be more willing to do though?  Is it socially more unacceptable to drop your trousers and deuce in the driveway or stick a gun in somebody's face and terrorize them into submission?  I suspect more people would be more willing to rob the liquor store than squat in the street. 

I believe even with the threat of an owner producing a gun; it is still mentally easier to deal with a monologue associated with being a criminal rather than an idiot!