Asking for directions (or just don't bother)

I headed to the post office to pick up a package today. I knew vaguely where it was, but in the end, I had to ask for directions....ugh. I HATE asking for directions in China, and I know most other foreigners do too. A few typical scenarios of direction-asking:

• Friendly people who tell you exactly how to get to the location of the place you are looking for. (ok I assume this is a scenario, although it has not happened to me yet)
• Disinterested people who point towards a road and say "not far" or give a time estimate.
• Rude people who don't even look at you while barely pointing in a direction. At worst, they don't acknowledge your question and just impatiently shake their hand "no".

Today was a classic example of No. 3:
I walk up to a security guard. "Excuse me, is the post office nearby?"
Not looking at me. "No."
"Well...is it farther down the road?"
A yawn. "No it's not over here."
"...is it back towards the Gulou roundabout?"
A head jerk that could have been in that direction. Or just a tic. "Yeah, it's not over here."
I'm starting to lose my patience. "Which street is it on then?"
"Over there towards the roundabout."
By this point I am thoroughly annoyed at how I've wasted 10 seconds of my life, so I just head in the direction I think it is and find it myself.

This kind of behavior is extremely 普遍. As far as I can tell, the behavior doesn't have to do with the person's age, the region, or whether the asking person is a foreigner or Chinese. The situation can be a shopkeeper lounging on a stool in front of her shop, obviously not busy, obviously a native, and be barely acknowledging a request for directions (and oftentimes any other kinds of questions.) It can be a college student walking in the same direction, who points towards the fork in the road and says unhelpfully "That way."

I can only attribute this to culture, even though I'm not sure what aspects of culture have to do with it. Do Chinese not like to give directions? Traditionally, do they think it's rude to ask strangers questions? Do they not know how to give directions? The best guess I can come up with is the Chinese method of describing location is different than how Americans are accustomed to, and also they simply don't see a need to treat strangers warmly.

In the end, I got my package (I thought it was from my sisters, but it was from Edward, so it was a really nice surprise) and took some nice photos of Gulou park area along the way.