You just hit on a peeve of mine. CC has improved over time but still doesn't always maintain a steady speed. There's nothing more frustrating than getting behind someone who slows w-a-y down on a hill, then the car finally downshifts and they're off like a shot... usually just as you pull out to pass them. Furthermore if you need it to maintain a steady speed you aren't paying enough attention to your driving; when I'm behind somebody I often shut it off when it's the only way to maintain a safe distance behind them.
I still can have a bit of a heavy foot, yet slow down in built up areas or places where there's apt to be traffic entering, or kids, pedestrians and animals on the side of the road. Often the people I just passed will then go blowing by me with no regard for reduced speed limits or possible hazards in the road.
One time I had to get home in a hurry, and was going way too fast with 3 cars right behind me. When I slowed down through town, all 3 went by me with no regard for the crossroad, crosswalk, or school zone.