If there are errors you still have to boot from the Recovery Drive to make repairs and that entails repeating the verification step. So why not save time and boot from the Recovery Drive in the first place?
Because booting into Recovery takes considerably more time than live verification and is a particularly time-consuming waste if it's not necessary, which, based on the DU pop-up, it isn't.
It seems as if live verification has reached the point at which Recovery is a fallback for when you can't boot into your regular volume rather than a day to day tool, unlike in the good old days when you had to boot into an external volume to run Disk Repair,
