This is definitely not as black and white as you put it. Today, where I live (53 degrees latitude, northern hemisphere), the brightest point of the day is just

This is definitely not as black and white as you put it. Today, where I live (53 degrees latitude, northern hemisphere), the brightest point of the day is just about 100W/m². That converts to about 12000 lumens, but that is only at the very brightest midday hour. Before that or after that, it is only about a third of that. There are plenty of days where it doesn't even reach 100W/m². On those days, daylight is more dim than regular lamps even at the brightest point of during the middle of the day.