Well that's because you didn't buy the car in the first place, the bank did.
In the aircraft case there is a good chance the owner owns it's free and clear.
As far as court, if you don't have a signed estimate and a paper trail on any additional costs, in most states including everyone I've lived in, you're up a creek. As I said, the lack of estimates and written acceptance of additional charges is where many of these disputes come from.
I disagree, most aviation people I meet chuck more money at things than they have to, heck there was just a post from a guy who bought a VFR ONLY diamond, he's blowing big bucks putting garmin glass into it, aviation folks spend the money.
Where I've seen the most disagreements is with unauthorized work, which some is a straight scam, but most is due to **** poor communication and completely avoidable by simply confirming over email or text.
You can try to make what argument you want, if you make it in court, you will find out how incorrect you are. Roll the dice and see where it gets you. If you can prove the mechanic is over billing/committing fraud, you're better off suing him than arguing, you'll get way more back out of it.
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