I'm not shocked. My parents are well aware that you have to watch a different channel for HD vs. SD (say fox for example, 8 vs 855). But they can't tell which they are watching unless they look at the channel number.
I find it totally amazing that they can't, since it is night and day. I keep telling me they should just give me their 54" Sony Bravia, since it doesn't do them much good anyways