You forgot cost of fuel(this alone likely offsets your imaginary rental cost), higher insurance rates for trucks(they kill people in routine accidents), cost of extra tires(trucks eat through tires), and higher cost of ownership in general. If you're using a truck as a work truck it'll also need to be replaced much quicker, adding to the overall cost.

Trucks are expensive for the owner and society.

Also, the majority of trucks in the US never do truck things. Like 75% are urban grocery getters. Americans have a serious consumption/ego/entitlement problem. Trucks are a great example of that problem. Instead of just saying, "I like truck. I want truck. I don't care it bad", people make up imaginary math that doesn't make sense instead of just admitting it's an ego thing.

The sad part of all this is the world laughs at the US over this stuff. We're a laughing stock and the people embarrassing us are proud of it. It's so shameful.

"I'm not that kind of American" has become a routine thing to say while traveling abroad.