They wouldn’t be better than the regular grocery delivery truck, but they have spare capacity when the demand for grocery deliveries has probably skyrocketed.
I wouldn’t think there are enough refrigerated trucks available in the world for grocery stores to all scale their delivery fleets rapidly at the same time.
Plus grocery stores wouldn’t necessarily want more trucks if they anticipate this pandemic-fueled demand being temporary. If the stores buy more trucks, the manufacturers build more trucks to meet that demand, what happens with all the extra trucks once this pandemic is over? Will all the new delivery customers keep getting their groceries delivered, or will many switch back to shopping at the store?
Given both those factors, UberEats style deliveries for groceries could make decent sense as a temporary measure.
I wouldn’t think there are enough refrigerated trucks available in the world for grocery stores to all scale their delivery fleets rapidly at the same time.