The McDonald's I worked at through college had a special lane, next to the building, for the delivery truck. The building and parking lot were designed so that deliveries would have as little impact on business as possible. The truck did not block any parking spaces or the DT ordering area, but DT customers WOULD have to drive around the cab of the truck to get to the window.

The truck could deliver directly into the basement. Deliveries were scheduled for non-peak times, but sometimes delays occurred.

Perhaps the truck was making a delayed delivery. Look at your store's set-up. Where are the doors from the BACK of the store located? Not customer doors, but delivery doors or "I have to take out the trash now" doors?

Perhaps the truck was scheduled to arrive at 5:00. With the right crew, all items could be put into the store and into the proper spots quite quickly. For some reason, the truck did not arrive as scheduled. Flat tire, accident on the freeway, items at the distribution center not ready, driver had to be called in on his day off....

Perhaps the truck was on time but the McD's employees were not up to speed. Called in sick, hung over, person with the keys was stuck behind some accident.

This wasn't an intentional, personal affront to you. It was something that happened. At a time that is generally not a rush.(Management tries to make sure that deliveries affect customers as little as possible. Imagine that.) Today, the store was busy. Usually, it's not, at that time.

This definitely isn't "bigotry". It's really not even "discrimination", although it's likely the store could have been designed so that deliveries would have less impact on ANY customers. If it's an older store, though, what do you expect McD's to do? Close the whole thing down so that they can redesign the store and the parking lot?