Requiring titles for tractors, ATV's, golf carts, etc. would present a huge (and hidden agenda) windfall for the gov't, at least in the states where personal property taxes are levied. I pay $155 per year personal property tax on my travel trailer, which is about the same value as my tractor, which I pay no tax on.
A coupla years back ,there had been a huge rash of ATV thefts, 4-wheelers. The Legislature started the process to title, thinking that would deter theft. Then the old property tax issue came to light and public sentiment shut the whole idea down.
I look at this issue as I see "hate crime legislation," totally unnecessary. There are already laws on the books, enforce and prosecutate to the max on those laws.