Alexander, you are correct about their problem with knowing who was driving
but they are supposed to be getting a picture of the driver as the vehicle
approaches so that they can match it to the files. My wife's radar ticket
included a picture that clearly showed her, my son, and me and my daughter
who were on a motorcycle going through just in front of and to the side of
my wife. If the van is doing it correctly they can ID the driver when they
compare it to the registered owner if it is the same.
Also I think that if you refuse to tell them who was driving, if not you,
they will then assign it to you and you will have to pay the fine. Kind of
like obstructing justice charge or something.
The best advice I have been given about radar tickets is to ignore the ones
mailed to you. If they bring it in person then they can verify you got it
but if they just mail it then they cannot prove you ever received it. It
worked for me about four years ago.
Also on the subject, There was a thread about overpaying a ticket and not
cashing the refund check they send back to you for overpayment. I have heard
from several sources that this works including a study done for a magazine
article that supports this. Anyway, Sorry for going off Linux so much. I do
apologize.  Cliff