Callisto - driving is also a dangerous activity which is why we take great precautions when driving, especially when it comes to having our children in cars. I wouldn't dream of speeding or having a child unrestrained in a car any more than I would dream of leaving a child unsupervised with a pony. Both are risks, both are risks I would be willing to take with my child because of the corresponding benefits, but both are risks I would want to manage and minimize.
I've also been around horses all my life and have seen numerous horses kick out because of flies. For example I have had a horse go balistic while ridden because of a fly in his sheath, I have had a horse kick an arena board only to disturb a nest of wasps I'll let you imagine the results, we have a lot of flat flies round here which drive the horses crazy, bot flies can upset a lot of horses, etc.
The one in twenty was not a statistical fact, it was a figure of speech. For facts on head injuries in children and riding see:
15% of injuries occuring while handling: content.karger.com/produktedb/produkte.asp?doi=10.1159/000084280&typ=pdf
head injuries causing 57% of equestrian related paediatric deaths
pediatrics.aappublications.org/content/89/6/1173.short
riding more dangerous than motorcycle riding, skiing, football and rugby
www.sciencedirect.com/science/article/pii/S0002961007001031
this one seems to show a correlation between injury and lack of adult supervision although I have not had time to read beyond the abstract
www.mja.com.au/public/issues/175_12_171201/holland/holland.html
this one ranks riding as second most dangerous only to pedestrians being hit by cars and above other vehicle accidents. It also cites head injuries on the ground from kicks as 30% and likely to be more severe than other injuries. It also mentions adult supervision as one of the injury preventing factors.
www.wisconsinmedicalsociety.org/_wms/publications/wmj/pdf/104/2/50.pdf
The "one child a year" was entirely anecdotal, but you can't compare fatality figures without mentioning participation figures.
To back up though the gruesome anecdotal fact:
www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-12620303
www.dailymail.co.uk/news/article-1192900/Girl-11-dies-kicked-head-pony.html
www.fox17online.com/news/fox17-horse-kills-vandalia-child,0,6346897.story
I don't think my post is hysterical but I do think yours is irresponsible in encouraging the OP in placing her child in danger simply because you took a risk that luckily failed to actualise.