This. I never saw more cyclists than when I was riding my bike to and from work. When you're in a car you either don't take note of them (not that you don't notice them, but that they're just an extra thing to not hit and then wiped from memory once passed) or you're just not out long enough to see them.
What might be happening is that an equivalent number of people using bike lanes and cars results in a much smaller impact and apparent usage on bike lanes.