Old bill in doing their job shocker

I think the key thing here is that the second example isn't them being deliberately unhelpful, it's cock up and lack of communication.

It's just like in the wire when ziggy shoots the greeks and the other half of homicide don't find out. Cock up, not conspiracy.

Sometimes the police are helpful, sometimes they are pretty stupid:

Helpful example:
My mate got knocked down quite badly on his bike last week, police were on the scene within minutes, were dealing with the guy that hit him straight away, had determined what happened and charging the guy there and then, as they realized the severity of the situation (my friend was very lucky to not get killed by oncoming traffic).

Unhelpful example:
3 times within the space of 2 months last year I got pulled over because I matched the description of a wanted gang member in the area apparently, the first time I was helpful because I respect they are doing their job etc.
When it got to the second time I actually said "Are you serious, I had this a few weeks ago, and got asked exactly the same questions and told exactly the same thing".
When it got to the third time I really lost my patience and said something along the lines of "are you taking the piss, this is the 3rd bloody time in 2 months, do you guys not communicate with each other or something?!". This time instead of being held for 10 minutes or so worth of questions, after a minute or two once they checked the plate against my name, I actually got an apology and then went on my way, annoying much!