I live in Norway (am American and grew up in the US). Spanking and the like is illegal here, has been since 1972 I believe. Children are generally well behaved here, so there are clearly other (and better, IMO) ways to deal with the completely normal variation in how small children learn to deal with disappointment, exhaustion, and other more serious reasons for tantrums during the early years.
I understand how frustrating it can be - I've dealt with my share of tantrums as a mother, and dealing with them has stretched my patience pretty thin sometimes. And
@Huntn I have loads of sympathy for you being in that situation, where speaking with the parents can be difficult or jeopardize the relationship but the behavior is driving you crazy. But there's generally a reason for a tantrum or bad pattern of behavior - anything from an undiagnosed physical problem to a lack of boundaries or consistency at home or even abuse. And in cases of abuse or neglect, the problem can bleed into adulthood if it's not addressed early enough.
This applies to normal toddler behavior, too, but sometimes "bad" behavior is the way a child tries to reach out when things aren't good at home. The child needs to get someone's attention, but if good relational behavior isn't being modeled at home, the child has no point of reference for how to get the attention needed - and the result is acting out.
Regardless of the reason for the acting out/tantrum, I really don't think violence solves anything. And don't fool yourself, it is violence, even if the best intentions are the motivation. You want the child to develop a good set of tools for dealing with the world, not only for navigating childhood, but in order to be good parents when their turn comes. Spanking is the easy way out.
I don't buy the argument that "I was spanked, and I turned out fine" that I occasionally hear. You turned out fine
in spite of being spanked. Yes, most people are psychologically robust enough to tolerate spanking, but that doesn't make it right, and it certainly doesn't make it the most sensible or creative option - just the easiest.