I rarely ever give a treat, if I do then it is thrown into their manger, usually a carrot or apple. However I think it is important for a horse to know how to take a treat correctly which is gently.
I often had small children visit the barn and I would allow them to give each horse a carrot. As many of these children were small I would have them hold one end of the carrot and let the horse take it. If they held it on the palm of their hand it rolled off!
No horse would snatch, if the child kept a hold of the carrot whilst it was bitten each horse would feel with their lips as the where little fingers were.
As a child the riding school horses and ponies were turned out on Downland where there were public rights of way. Opposite one of these fields was a car park and people would go an tidbit the horses across the road. Notices were there to be ignored.
This was mainly a summer thing when tourists were about.
All these animals were used in the riding school and were well mannered. Non ever thought about kicking or biting.
One day I was just going to catch some of the ponies to take into the stables. A woman was walking down the hill with two children, one, about 4 years and another older lad. One of the ponies walked across towards her. The children were nervous so she put the older lad to one side and lifted the younger. She also was carrying a bag.
She was some distance from me. The pony suddenly put his ears back and lunged at her, he took a good bite to the child's arm.
I know this was caused because people fed them, and he was annoyed she didn't have anything.
That pony had been in the school for about eight years, he was not a biter but had learned to expect and was annoyed when he didn't get.
He never went out in that field during the summer months again.