The announcers don't have any more insight into the call than you or I watching the same clips. They're not rules experts. That said, they're right; most refs would let the hand to hand combat go, but the trip is foul anywhere on the field. As for DOGSO, @KCbus is correct above; the key element is that when you commit the foul you take away a goal scoring opportunity, but when the ref awards a PK you have been given that opportunity back. So if the scoring opportunity has been restored to you, you haven't been denied anything.