How is it that someone can come from another state, do a hit-and-run, and get away with it?

i was involved in a hit-and-run accident the other day. this woman sideswiped my car while we were driving on the parkway, and i pulled over, and she pulled over briefly and then kept going. i got a glimpse at her license plate, and i saw what the plate # was. However, i did not see what state it was from, i only knew that it was not a New York state plate (I live in NY). The cops came shortly after, and i gave the cop the plate # and description, etc. He ran the plate, and said it was definitely not from New York state, but without knowing what state it was from, there was no way to trace it. He said that even if they knew the state, nobody was going to go to that address to give the owner a ticket, as the hit and run is just a “violation.”

So therefore, the person who did it gets away with it. How is it possible and acceptable that someone can get away with coming to another state and doing this and getting away with it? Why is there not a national database of plate #‘s or some system where different states have different numerical sequences for their plates?