[mikecane]

>>>They could get that region-level information already from ISP routing info.

I think they want to know you are where you say you are. You'll find if you travel out of the area -- particularly out of the entire country -- you won't have access to entertainment you had while at home due to these regional restrictions. Just think of the times when you've gone to the BBC website to view a video only to be told you can't have it outside of the UK (the BBC license area). (Note that I'm assuming you're in the US although your use of "postal code" likely means you aren't.)