I think that their arrests are not controversial and therefore not newsworthy because the local authorities cooperate rather than obstruct their efforts. Yes, there are more because there are more there. My point was while there are many more encounters, they are rarely controversial or dangerous because local authorities aid their efforts. Including most arrests being affected at their jails who hold them at ICE requests and hand them over rather than releasing them into the public.
I shouldn't say "I think" though. I spent hours researching it. The reality is, it is far far safer for the public in states where the local authorities cooperate. Also, safer for illegals who are not criminals as they are not being caught in sweeps and included in deportations.