I'm an audio mixer for several of the national and regional networks. I deal almost exclusively in live sports, and I can tell you we are monitored to a ridiculous degree. We have averaging meters in our trucks (measured in LKFS), and the TOC monitors the show AND commercials (in DB on a 3s average). The TOC logs the averages with timecode and video thumbnails (for reference) and saves them, as they are the only defense they have against CALM complaints. The TOC is quick to notify us during the show if we're too loud or too quiet and the averaging is out of compliance.
The problem is, no one at home is smart enough to know the difference between a national spot, a local spot, and a spot that your cable provider inserts. So the complaint becomes "Fox Sports played a loud commercial!!1!!!1!!!one!!!" when the culprit is actually the Comcast head-end in Gary, Indiana.
Between the meters, the logging, and the constant monitoring, broadcast is jumping through a lot of hoops to be CALM compliant. But the networks don't have end-to-end control of their signal, and the end user is at the mercy of their local cable headend. Almost all of the problems you experience happen there. I can't tell you how many times we find a surround downmix where the announcers are almost inaudible, because a cable operator (and sometimes even a satellite provider) is doing an improper downmix, and the 4.1 channels are blowing out the center on the stereo feed. The networks try to QC as much as they can - most of the network offices have receivers for every cable and satellite (and FiOS, AT&T, etc) service they can get their hands on, and constantly monitor as many of them as they can - trying to find and fix the problems proactively rather than wait for the vague and usually inaccurate complaints to roll in from the FCC.