If you've got a photograph of the meter with time on it, that's partial proof.

But you raise a good point - with all the technology we have, you'd think the meters should be designed to create a record of time expiration, which would prevent the "he said, she said" sort of thing.

If a meter maid gave me a ticket when I have time on the meter, and I haven't been feeding the meter - i consider it robbery, and I'll report it as such.