…ally, they are flexing. Peruse this thread of people showing their midsections flexed and unflexed. Look at Kayla Itsines of the BBG empire doing an actual workout, where her abs are not really visible, vs. one of her posed pictures. Take a scroll through and you will see she is not only flexing but she basically always cranks her body to the side in good lighting to emphasize the definition. Which is fine! But know what you’re looking at: a good solid flex plus chiaroscuro lighting dramatically improves the appearance of abs. Unfortunately none of us walk around like that, so take any posed shots you see with a grain of salt and do not compare yourself to them.