On SUVs with a weight of more than 6000 pounds, a business owner could take up to $100,000 of depreciation off their taxable income in the first year. It made those big luxury SUVs very attractive to doctors, lawyers, real estate agents, and so on. Toyota made a mistake one year with a new model of their large SUV that came in at just under 6000 pounds...
The loophole seems to be closing, and it is complicated, so consult your accountant before buying one.
As I remember it, "SUV" was originally deemed part of the off road &/or utility (hence the name) collection and import duties were less than for sedan/streeters.
The initial boom came in Japanese imports and US manufacturers jumped on the bandwagon.
I also note that out here in utterly non-rural Los Angeles county the vast majority of SUV's (all two wheel drive) are driven by women. I am certainly not aware of any tax break to the buyer as I grudgingly pay off a 2004 Explorer.
Must add that I made the lady buy a V-8, knowing the fuel costs, because every six I drove was a risk in freeway traffic where acceleration is often safer than breaking.