Arbitrary in the sense of non-essential things that governments spend other people’s money on.

The fact that most people don’t agree is why tax is taken by force.

That's not what arbitrary means. The fact that someone is spending on something non-essential doesn't make that spending arbitrary. Lipstick is non-essential but that doesn't mean the spending on it is arbitrary.

I'm quite confident that a lot of thought goes into pretty much all government spending, even if a proportion is misguided, counter productive, and non-essential.