UPS is a business. Their MO has always been Profits before People.
Amazon is a business that appears to have shifted a large portion of their volume for today over to UPS. Amazon did this to protect their employees, shield Amazon from lawsuits; OR most likely; It was a "lets leave it up to the professionals today"
We get paid to deliver parcels. Prepare for the extreme temps. If your Package Car and DIAD fail; YOU won't.
Extreme temps are no where near as much of a problem as even 2 inches of snow is.
With snow; you have to worry about every maroon (as Bugs Bunny would say) out there driving too fast for conditions, crashing into you, etc.
With extreme temps; you are your own worst enemy IF you don't prepare.