Another commercial I don't understand.

Okay, so somehow there are two employees, one for Pepsi Max, and one for Coke Zero, presumably blue collar, probably truck drivers (white collar workers would probably not be wearing shirts with patches on them and baseball caps) who both end up sitting near each other at the counter at a diner. The Coke Zero guy, who was already sitting down when the Pepsi Max employee walked in, is drinking a Coke Zero, but sees Pepsi Max guy start drinking a Pepsi Max. The Coke Zero guy stares at the Pepsi Max longingly. They chat, the Pepsi Max guy moves up next to Coke Zero guy, and he confirms Coke Zero guy's question, which is whether Pepsi Max had zero calories (it does). Pepsi Max character offers up the can of Pepsi Max to Coke Zero guy, who takes it, has a long pull, and then confirms, skeptically that the drink has zero calories. He then takes another gulp, which Pepsi Max guy captures on his phone, and when Coke Zero guy asks him why he's taking that, Pepsi Max guy responds that he's putting it on youtube. The camera then takes us outside of the diner, and all of a sudden Pepsi Max guy and Coke Zero guy come crashing through the window, fighting, presumably because Coke Zero guy was concerned that being seen drinking Pepsi Max would get him in trouble with his employer.

The fact that this commercial is terrible comes out simply from a single viewing. But possibly my main problem is that I don't understand the underlying reason for why we should believe this commercial. And, of course, I get that lots of commercials kind of (or entirely) have nothing to do with selling their product - it's a different type of approach, and that's fine. Let's restrict ourselves to commercials that talk about one product being good by demonstration, or one product better than another comparable one. Usually they either show people, who we're at least meant to believe are real people, talking about the product, or they show the two products at work. In the former, in theory, if they're real people, that gives some sort of credit - real people think this product is good. In the latter, two, say, cleaning products are used side by side, presumably the results of one are much better than the other, and if we are to believe this is honest, it could persuade us. In this commercial however, the characters are clearly actors. There's no reason we would believe otherwise, from the way the commercial is filmed, to the dialogue, to the comical fight scene at the end. Soda isn't a product we can see in action - there's no way for us to judge the effect of taste from watching, like we could with a cleaning product. So basically what's happening is a paid actor who is clearly a paid actor acting as a Coke trucker is claiming how great Pepsi max is. Why on earth would anybody believe this? It's not just that the commercial doesn't work to me; the concept doesn't work. I don't get it.