Meh, it's bad timing or bad luck but it's not the end of the world to just wait a few minutes for the cars in front of you to leave. I can understand being frustrated in the moment, but at some point you just have to cool off and accept that it is what it is. It's just a few extra minutes to you, but for the people inside, it could mean using equipment for your order that could otherwise be cleaned while the last few cars are serviced.