Airport Fuel Pumps
Why do self service fuel pumps ask for your tail number?  What do they do with it?
1 Replies
So if there is any problem discovered later with the fuel, they can track down all the planes which got it.  That has happened in the past, and the fuel providers have done various things from paying for the plane to be drained, flushed, and refilled to buying new engines for a bunch of planes.  It is very much to your advantage to be truthful when you put that number in.

And no, despite the fears of some of the tinfoil hat crowd, the black helicopter folks aren't using the data to see where you've been.