Perhaps parents can learn the principles of tantrum control by watching a few youtube tantrum videos.
Many tantrums are the results of misdirected parental attention, as illustrated by this youtube video:
But many parents can't seem to figure this out. At 1:15 in this next tantrum video, the parent hits upon the right strategy, but does not know how to follow through. Notice that the second he directs his attention from his tantruming daughter and redirects it to praising a well behaved kid, his daughter's tantrum starts to abate and she starts cooperating. He should have continued to praise the other kid and should have praised his daughter for putting on her shoes. But instead, he reverts to his usual pattern and the tantrum revs up again:
Most parenting books are not based on evidence from research on how to control unwanted behavior, so they give poor guidance and even advocate methods that are known to increase unwanted behavior. One good evidenced-based parenting book is the Kazdin Method by Alan Kazdin, head of the Yale Parenting Center and former head of the APA:
Most unwanted behavior can be addressed by ignoring it and praising the opposite. Give your kids lots of praise and facetime when they are exhibiting good behavior and moving toward self-control. It OK and good to give a kid having a first tantrum a bit of empathy, but you need to move to ignoring pretty quickly to avoid reinforcing unwanted behavior and thereby getting more of the behavior that you don't want.
Not all tantrums are attention-driven. Tantrums have other causes and it's good to try to ferret out the cause. Certainly a kid's early tantrums are initialy driven by frustration. It's only later that a kid learns that he can control his parents via tantrums, if the parents fall into the wrong response pattern.