give it a try.
grab a wheelbarrow, fill it with feathers, and see if you can push it up a nice hill.
repeat filling it with lead shot.
get back to us on how it went.

the absurdity is in play due to the *selective* enforcement of realism. The cart is realistic. 3 stamina foods and hauling 100000 pounds of metal, taking 'breaks' where you toss it on the ground and pick it up again, repeat until home... or ride the lox while carrying said weight... oops.