I wonder is the truck was making a delivery. Sometimes they have to block off access to some parking spaces or to the drive thru so that can make their deivery. Some store unload directly to the freezer and fridge walkins by small access doors outside of the building which might not be in the best spot

I agree with you that if the truck was not making a delviery or had finished unloading the truck then it should be moved. However if they were in the process of unloading, then you have to understand that they need to get the food into the store so they are able to make that Egg Mcmiffin for you.