If Mrs.Trunchbull hated kids so much

Good point

Exactly, it's just like what my mother was talking about tonight. She was talking on the phone to a friend, telling her about an old neighbor we used to have, who hated people so much, hated my mom, called the police and fire department every time we barbecued saying the house was on fire, called and hung up on my mother for 6 months, the one time my mother called her, she called the cops and told them my mother threatened to kill her. She was the most miserable bitch who ever lived, she was given an ultimatum because her husband worked at the same place as my mom, and the boss told her if she caused anymore trouble for my mom, her husband was going to get fired, so they had to move. Some years later, she came back and told my mother she has the BEST job in the world, a guard in an all men's prison and she could beat the crap out of the inmates and do whatever she wanted to them and there wasn't anything they could do about it.

I think it was maybe originally Roald Dahl going back to an era when clever women had very few career choices. Teaching was one of the few options open to them, so a lot of female teachers felt frustrated and trapped. Especially just after the World Wars, when a lot of women had been made single parents/ lost their chance for a family.

Of course, the Trunchbull is just a stereotypical frustrated teacher, who enjoys the sadism rather than doing athletics, what she actually loves. Presumably she was doing it to keep an eye/ bully Miss Honey as well, to keep her hands on the cash?

I've often read interpretations that say the Trunchbull deep down wanted to prepare the children for the harshness of the world. Her line "glad I never was one [a child]" suggests she may have had a harsh upbringing and maybe her way of doing things was out of toughening the children up.