Yes, our brain is good at this - but it still takes some capacity in processing to do this. I guess the point is: if you have a simple, high-contrast background - your brain needs less capacity to process it.
You got evidence to back that up?
The human body is designed to desire and consume the maximum amount of feel good tasty food for maximum energy but we are finding that the evolution of the human body is not designed to actually accept such massive consumption despite our desire for such food. Our bodies do not handle the highest capacity consumption instead they have narrowly evolved to fill a strangely specific niche.
Same with our eyes. It may seem easier to like high contrast designs but our eyes through millions of years of evolution are not optimized for high contrast signs since those things never existed in nature.