Yes they do come through. Also you have to realize that rr.com covers a HELL of a lot of IP space. And, as Telarin suggested, about 8 million RR subscribers.
Each division has their own email subdomain.
nyc.rr.com = new york city + new jersey
san.rr.com = san diego california
ec.rr.com = kansas city (no idea where "ec" comes from")
etc. etc.
Abuse tickets are assigned to and handled by each division, determined by the originating IP in the spam headers. In my division (not the largest), we get 25-75 abuse tickets a DAY. I can't fathom how many the NY City division must get.