Yup, that’s right. If it collapsed under her weight, it could have collapsed when 2 people walked on it, or 1 person with a loaded shopping cart, or 4 kids, take your pick. A person large enough to make in an unreasonable load would not be able to walk under their own power in the first place.
Perhaps, but a shopping cart or multiple people on that piece of concrete would distribute the weight (load) far more than a single fatty stepping on it. The PSI from the ball of her foot (a single footstep) would be huge.