Insurance companies

[Ginger]

you've got it backwards.
if they want proof, they need it before they take your money. bottom line, you pay to insure a $12k car, its a $12k car.
"motivation to defraud" and what not is secondary to the fundamental principle.

If they want proof all they need to do is put it in your documentation. Nobody's saying that there shouldn't be disclosure of receipt requirement, we're saying that if you want it covered, then you'd better be able to prove it's worth.