Look again. The fence iron gets longer as you go toward the street, more than just a perspective thing.
I'd estimate a foot of drop from the garage door to the curb (not the street, which would add another 4 to 6 inches, judging by the tires on the vehicle parked next to it and depending where you were along the curb--It is higher at the alley entrance).
You'd need that much grade for runoff in case of a severe thunderstorm, too, as the whole square footage of the house and the 'yard' would have to drain away from the house or flood the garrage.
Note, too, there are a couple of significant ripples in the alley, really evident at the border between the pavers and the alley.
Thank you both for pinting that there IS a slope (I didn’t see it til I followed your visual cues on the monitor screen). It is there, though slight, but not pronounced enough to cause the ‘roll’ that is being alleged.