"Even worse are the people with HD TVs that don't even use the HD channels of whatever they're watching"
The situation is made worse by the fact that the 'old' channels (BBC1/2, ITV, C4, C5) are still numbered as channels 1-5.
For people like my ancient Mother, those are the historical channel numbers which she's always used. She rarely strays beyond channel 5 and can't grasp the concept
of adding 100 to get better pictures. She also cannot figure how to use the menu system to see and choose what to watch.
I'm sure there are many like her.
I therefore suggest as a first step that those SD channels are swapped with their equivalent HD (e.g. Channel1 becomes HD, 101 becomes SD, etc).
That way people will be forced to think about what they're doing!