Regarding the data seen at the top of the picture on SD programming of broadcast channels, before retirement I was part of the engineering staff of a major cable company. I spent some amount of time researching this issue.
Video line 21 is the last line of the Vertical Blanking Interval (VBI), normally this line is out of sight and Closed Captioning (CC) data is inserted on this line. Line 22 is the first line of active video, what is not commonly known is that the FCC (1) gave Nielsen rating service permission to place data on line 22. The data is a function of Nielsen's Automated Measurement of Lineup (AMOL). Google Nielsen AMOL to see more info.
Older picture tube TVs overscanned the picture, so the data on line 22 was not a problem. Today's plasma and LCD displays don't need to overscan, so under the right circumstances will display the data.
Only some of the local broadcasters had the problem, so I worked with their engineers to see if it could be eliminated. Talking with an engineer of a station that did not have a problem I learned that their local MPEG encoder could be adjusted to eliminate the problem. So I carried that information to one of the stations that had the problem and learn that they had an older encoder that didn't have that feature. Then I sugested that they rewire the video so that the Nielsen data wasn't inserted on the digital feed, only the on the analog signal. They did so, but it only half helped as the network inserts data on one field and the station inserts on the other field.
I also saw CC data on some of the offending stations.
So I finally threw up my hands and moved on to other pressing problems.
My thoughts are that there is a mix of problems here, TV sets are being designed to a standard that the FCC allowed to be bastardized and TV stations are not paying attention to addressing the problem at their end.
After February of next year analog AMOL will be useless in the digital domain, but programming may still have it embedded and it may still be an annoyance.