In Illinois, if you register a car and they see you bought it from out of state you’re going to get a tax bill for the difference in what you paid in tax there and what you would have paid if you’d bought it in your home juristiction in Illinois. There’s also a “use tax” form on their income tax form that asks you to report and pay taxes on any out-of-state purchases.
We own a boat that we used to sail up to Lake Erie from FL. We're part-time Ohio residents. But, OH's department of taxation began sending agents to marinas and started documenting the boats that were in the marina. If they had an out-of-state registration, but were registered to people who lived in OH (even if they were only part-time residents), those people would get use-tax bills from the state.
As a consequence, we no longer take our boat to Lake Erie anymore. Who loses out? The state of Ohio because we no longer pay the marina operator for dockage, or fuel, or supplies. We no longer pay the riggers or local laborers who work on or service of boat. Everyone loses all for the sake of Ohio trying to maximize tax revenues - they can't see the forest through the trees.
These are oppressive tactics that I refuse to comply with. I often drive to Wisconsin and buy items to avoid Illinois taxation (especially Cook county and Chicago taxes) and I will NEVER fill out a use tax form. My accountant says let them try to prove it, screw democrap governments.