it's not accurate to say that all supermarket delivery vans in the UK don't have air conditioners. Some delivery vans may not be equipped with air conditioning systems, while others could have them installed, depending on the make, model, and age of the vehicle.
It's worth noting that delivery fleets can be composed of various vehicle types, including older vans that might lack modern amenities like air conditioning. However, many supermarkets and delivery companies have been working to upgrade their fleets and improve driver comfort, which could include providing newer vans with air conditioning.
For the most current and accurate information, it's best to check with specific supermarket chains or delivery companies in the UK to inquire about the features available in their delivery vans.