Is there a broadcast engineer who hasn’t heard the clichéd accusation that TV stations turn up commercials? Ever heard of a broadcast TV station where that actually happened? Me neither. Pre-automation master control audio operators were viewers who got annoyed like everyone else. If something sounded too loud, most good master control audio operators ignored the VU meters and didn't reach for the monitor speaker volume knob. Good operators potted down the source gain at the console, and people still complained.
Typically, downstream from the from the Master Control audio console were various audio processing devices designed to prevent over-modulation at the input of the STL and transmitter. Those devices generally fought with changes in levels and dynamic range. It was a problem that kept getting worse.
Audio-follow MC switchers, broadcast automation, crazier producers and more powerful audio compression techniques made the loud commercial problem so loud the United States Congress felt the need to take action. Can digital television technology fill in for the missing broadcast engineer with a critical ear on the demod and a hand on the gain knob? The FCC and the industry have set out to do exactly that for a number of good reasons.