The vast majority of people don't commercially depreciate their vehicles, so while this does apply to some, it's a relatively small group.

In my huge group of friends, I know one person who does this with his truck, and he readily admits that it involves lying to the IRS and it fraud. Everyone else with a big SUV just prefers them to minivans.

There is also a gas guzzler tax that only applies to cars. If it was applied evenly, most trucks and SUVs would be paying a tax penalty for poor mileage. So there is a kind of indirect government subsidy to bigger vehicles. It is a dumb policy, but it's not why people like SUVs.