Yeah I didn't think about the monetization angle when I typed that comment, you're right. Some even redirect NXDOMAIN results to a "search" page full of ads (T-Online in Germany did this until recently).
Last I checked Verizon/Comcast does this regularly in the US, and I remember it being a persistent annoyance. As someone who's geographically blessed enough these days to have the option of an alternative ISP, god bless RCN.
Unless it changed within the past year, Spectrum redirects NXDOMAIN to yahoo search results.