Likely long escalating ramps (like conveyor belts) actually designed for carts. They are supposed to be made so that the wheels of the cart catch in the matting of the belt/ramp, preventing the carts from rolling on the incline until the end of the belt/ramp is reached.
We've been in a hundred such large stores in Shanghai, including many, many locations of that Lianhua chain mentioned.
Sometimes, it just doesn't work that way.
Hmm interesting info, Thanks.
It would appear that in this case the resourcefulness of the idiot had not been taken into account.
The cart they where using didn’t belong to the shop, hence no safety features.
Cheers.