I probably don't agree with your spending decisions. What do you want to call if I were empowered to make better ones on your behalf? Tyranny is a good word for it.
1) Tyranny is different to cruelty. Tyrants don't have to be cruel.
2) How is this not oppression? Someone wants to buy their son a chemistry kit, the son is probably all excited about it because there is something dangerous and exciting to learn about and then some random enforcer is coming in and stopping that from happening because they disagree with that family's value judgements. If that isn't oppression in the small, oppression may not exist. Oppressors can all say that they're worried about the safety of the people they oppress - that is a common argument oppressors make if they feel like justifying themselves. Imagine that line coming out of the mouth of a Communist Party spokesperson over in China, they aren't implementing their policies out of a sense of malice - they think they are good for China.