Jesus ****ing Christ Mark.... you can be helpful but you also sure like instigating shit and get REALLY defensive if anyone hints you're wrong.
Now, this may vary by state, but for the most part it does not.
A private sale, by default, does not come with any warranty or guarantee implied. Unless the documentation says otherwise, that's how it is.
Also, "does this on the side a few cars per year" doesn't mean it's a side BUSINESS.
I happen to go through cars fairly quick, and sometimes even purchase a flip or two in a year. Hell, I have 2 in my garage right now. Most states have a law on how many cars per year you can sell without a dealer license. If you are below that threshold, no business license or any special rules apply. You are just a guy selling a couple cars you don't want or need. Period. No business, no warranty, no promises, no liability once the bill of sale is signed.
Also, and this part doesn't vary from state to state: Taking someone to small claims court because they didn't disclose that your car had
wheel locks and either lost or didn't even know about a key(they may have never even removed the wheels while it was in their possession), is petty, hilariously childish, and honestly supporting such an absurd notion makes you seem like all the other sue-happy people out there that just can't leave other people alone or make their own damn way in the world.