I didn't want my 4 year old unnecessarily traumatized. He was frequently sick and had to see doctors regularly. He had enough baggage over that, and was later diagnosed with a genetic disorder.

I knew what I was doing. If a parent doesn't know, sure, get the IV. But if a parent does know and wishes to spare their child some pain, I see no reason that should not be supported. The comfort of my children mattered to me. I cannot imagine that it wouldn't matter to most other parents.

I think 3131s's theory is that the amount of pain from a needle is much less than say scraping your knee, hardly traumatic, and is guaranteed to work better, faster, and more reliably than a spoon. Why risk the spoon not working (and therefore further dehydrating the child and increasing risk of something really bad happening) when all we are talking about is an IV, not something actually traumatic like an amputation.

Every IV carries the risk of thrombosis. So I would avoid it, if I can.

If the IV reduces or eliminates the discomfort of dehydration faster (which it seems it would do faster than hours of spoon-feeding?), that might also actually reduce the overall trauma level.

This varies a lot. Some people seriously don't deal well with needles. Your cavalier attitude towards them is not universally shared.

This is odd to me - how would a four year old develop a fear of needles? At worst they're an instantaneous sharp pain that lasts milliseconds, most of the time they aren't even felt...

I believe the moral of the story is that with education and encouragement, kids should not get dehydrated enough to ever require an IV.