Good point. That's why I listed voting and jury duty, I was summoned to serve on a jury multiple times, and I always feel weirdly excluded when I have to explain that I'm not eligible. I know it can be a burden though..
At the airport, citizens and legal residents always share a line, in my experience. We tried to maintain Global Entry for the whole family for a while, but as the entry process got streamlined for citizens and GC holders over the years, the advantages of that vanished.