This is obviously anecdotal, but I've had to call 911 a couple times (I live in NYC, things happen on the subway). Explaining where I am took up 75% of those calls. They want very precise details and it's sometimes hard to answer to the level of detail they want.
Example: I once had to call 911 when a woman fainted in the middle of the platform. I spent (seriously) several minutes explaining my location to the 911 operator. I was waiting for a train that only has one platform - the train goes east/west, and eastbound stops on the opposite side of the same platform as the westbound. The 911 operator couldn't process this and kept asking me whether I was on the westbound or the eastbound platform.
We wasted a few minutes going back and forth on this - which could've been critical if the woman was in need of urgent medical care.