One, there is no crime here. This is a civil matter and it is handled as such.
Two, if you would have read the code sections I linked, and/or the paragraphs I copied and pasted you would have seen the following:
The issuing agency shall not be required to produce any evidence other than the notice of toll evasion violation or copy thereof, information received from the department identifying the registered owner of the vehicle, and a statement from the officer or person authorized to issue a notice of toll evasion that the tolls or other charges and any applicable fee was not paid in accordance with the issuing agency's policies for pay-by-plate toll payment.
An officer's statement that he/she witnessed or reviewed photos your vehicle being driven through without paying the toll or an officer's statement that he reviewed photos showing your vehicle doing the same, is evidence enough to justify the citation and to provide sufficient cause to believe that you will lose the first level appeal, the second level appeal as well as the court hearing. And by the way, the third level appeal will cost you an additional $25...
Three, the code sections cited here are from the California Vehicle code, enacted by the state legislature and NOT written by the agency handling the toll collection and the issuing of citations, collecting the penalties... etc.
And so with all of that, the only thing that is unreasonable is not only are you admitting to committing the violation, but you even describe how it happened, and yet you still want proof that it happened!
It is not unusual but rare that we get questions about toll violations... So you might not get this wish either! Sorry!