You're swapping dynamic range and exposure control. Your examples of dark rooms and bright light sources are examples of great exposure control, not dynamic range. Dynamic range is the difference in light intensity from pure black to pure white in your sensor. Modern sensors are also extremely good at dynamic range though, much better than film and apparently much better than our eyes as well. From a quick search our eyes are at 10 stops of range (2^10 ratio from white to black) and modern sensors have gone past 15 stops and are pushing on 20 apparently, which is just amazing.