But I also see so many parents putting their babies and very small children on full size horses which doesn't seem so safe to me either. It seems like it may be a safer solution to train a mini for the small children of those that MUST put their child on a horse as soon as possible.
Actually, having been one of those kids who rode both a mini-burro and full sized horses from the time I was very
small, it's actually safer to have a full sized horse for children IMHO. That way, the horse is large enough to have had good and proper training by a knowledgeable adult and is large enough that an adult can get on them occasionally for a tune-up if needed. Plus, you don't have to worry about the child outgrowing them in only a year or two.
Just as a for-instance. When I was a toddler (2-3 years old), we had a miniature burro that I was riding. Because he was too small for anyone other than me to ride, the whole riding experience was new to both him and me. He gave me my very first experience with being bucked off and getting road rash.
Then, when I was 4, I moved up to a 16 hand, 1500 pound roping horse...and I never ended up with so much as a scratch from that guy, even though I rode him for years and years at all speeds over some very rough terrain.
IMHO, until a child is capable of controlling the horse for themselves (stopping, turning, and getting controlled forward motion), then the child has no business being on a horse of any
size by themselves. They should either remain on the lead-line or riding in front/behind an adult or older rider.
I honestly think that my experience (other than the episode with Olen, the burro) was just about as ideal as a person could hope for as far as learning to ride. Whenever I was an infant-toddler, my Dad would sit me in the saddle in front of him when he was warming up his show horses
As I got older and wanted to start riding the horses for myself, either he or my older brother would simply give me the reins and sit passively behind me like this (this is me and my, then, 3 year old niece)
As I got a little older and gained proficiency with my cues so that I was controlling the horse all by myself, that's when I "graduated" to my own mount by myself...Olen
Other than being basically unbroken, he was a decent little critter. We went a jillion miles together and he taught me a lot, but not much of my time on him was relaxing and I picked up some bad habits from having to deal with him. Riding him was work and we had a lot of issues, some of which I didn't manage to overcome in my riding until I got on a more suitable mount...which happened to be Old Buck
Anyway, sorry for the whole tangent, but that's why I
think average sized horses are better for children than minis or ponies, simply because of the training they can get. It is very hard to find a knowledgeable person small enough to put any decent kind of training on horses that are child-sized.