Good point, I forgot that too. Here in my state, yearly inspection is a bit of a PITA but pretty cheap, but there's a "car tax" ("personal property tax") that's usually hundreds or even into the thousands per year for newer cars. Other states have something similar but they call it a "registration fee".
It's once a year here, for cars as old as mine. It's not a big deal though; it takes less than an hour and you can usually go without even having a reservation. Costs less than one tank of gas.