I think where you're tripping up as that the statement should be "modern day policing in the US" developed as a response to Jim Crow laws. Focusing on the fact that the idea of policing existed before and in other countries is missing the point, possibly deliberately. It's also ignoring the fact that there are aspects to the US law enforcement and judicial system that are very unique to this country. That is because slavery/racism is woven into the fabric. It's not just something that kind of happened along side it.