Basically this problem is absolutely solvable if you actually want to
Can you imagine working a job like this when it's cold outside and you potentially had ice the night before? And to solve this problem you'd basically reinvent the car/truck.
In icy conditions, it's likely safer for most citizens to have delivery done by bicycle. They're slower and lower mass compared to a van.
In cold, the delivery person can just add layers. And, they'll be moving more, so in all likelihood, the additional layers required is minimal. It's not like a UPS van is super warm inside - not with the driver constantly opening the doors and hopping in/out.
It simply boils down to priorities. Do we want cheap/easy delivery to merchants or do we want safe pedestrian and bicycle zones for customers. Or, is there a magical balance point in the middle?
Also I highly doubt these tiny bicycle tires can handle a pallet of bottled water or beers. They will just get crushed.
By the way, why is it so important that deliveries get done within an hour?