I'd guess—with limited judgement due to the image
being captured with a potato—is that the fine is just.

As far as I can tell, the woman in the passenger seat is
not wearing her seat belt at all, but is wearing a loose
clothing garment such as a sari—the top fold of which is
running up and under her left armpit.
We should be seeing the alleged seat belt quite clearly, as
we do for the driver.
As far as the upside down and reversed number plate
image goes, I'd just write that off as some sort of technical
gremlin at work. Her number plate could've easily been
captured earlier on, or further down the motorway maybe?
The easiest way out of this is for the driver to get her
daughter (the alleged passenger) on the day to sign an
affidavit stating that she was wearing a seat belt during
that fateful trip.