She told the cop, "I was going the same speed as the traffic around me". Which, I believe is an admission of guilt.
Well, I have been driving from Wisconsin to Illinois every weekend on I-94 for probably the past year, so I know the traffic patterns pretty well. I can say clearly, without a doubt, that traffic does not move at 91 mph on I-94. The average pace is about 73 mph. I can drive anywhere from 70-75 mph and no one flies past me like Im standing still.
My advise, either you 1)
talk with the appointed attorney, plea no contest and they may lower the ticket to either 24 (no suspended license) or 19 (4 points) mph over, depending on how nice the appointer attorney is feeling that day. She wont get a suspended license, but she will still pay the larger fine because they want their money.
... or 2)
get a lawyer, pay the guy a bunch of money and still see the same result.
Fact is, your wife has a history of careless driving. If she pleas not guilty, it will get an actual court date, you will be paying court fees, lawyer fees, and wasting a lot of your own time only to have her history of suspended licenses, DUI's, accidents, and all other moving violations she has had in the past blow your defense out of the water.
I would recommend the no contest option, hoping it gets lowered to a lesser moving violation.