LOL. I would've agreed with the OP before I had kids. My daughter is the sweetest little thing you can imagine but every once in a while she will get fussy. I never ignore her. I try to discipline her with stern words and if that doesn't work, I take her somewhere quiet and try to calm her down. I wouldn't say there's "no way around it", but parents have a tough job and you need to give them a little leeway.
But don't for a second imagine that you can always control kids. It's a physiological thing. Their mind and personality simply aren't fully developed. They can't show the same kind of restraint as most adults. I wonder what goes in the households of those claiming that their children never lose control - do you just beat them into submission?
This particular kid definitely seems to be suffering from bad parenting if he called his mother a *****. The OP's friend could've resolved this very reasonably, but chose to stoop down to the level of a bratty child. If that kind of behaviour was unacceptable coming from the child, imagine a grown-up behaving like that.