For your consideration ...
There is no law that can compel a person to bear witness against themselves, or to provide, voluntarily or not, evidence against another person. The burden of proof falls on the police dept that issued the ticket. There is an address on each notice that has an address with which to mail any contestation, well prior to any court date. Why would someone voluntarily admit guilt by blindly paying the fine, or supply any evidence, (ratting out someone), if there is a way to bring into question of who was actually "operating the vehicle"? Being unclear of who was "operating the vehicle" is rational. Saying that one has multiple vehicles, with multiple drivers, and not being sure who was driving at the time, is enough evidence to bring doubt into question, and satisfies the requirements of (i) and (ii). And, if after sending that, if the court still wants to see you in court, state the same, and in addition demand a proper investigation by the police into who was the actual driver. What does one have to lose? $40 and court costs? By not challenging these money grab schemes, it will continue. No agency is going to spend time investigating something over a $40 questionable citation.
Here is State law that applies to a challenge ...
https://law.justia.com/codes/maryland/2022/transportation/title-21/subtitle-8/section-21-809/
(3) To satisfy the evidentiary burden under paragraph (1)(ii) of this subsection, the person named in the citation shall provide to the District Court a letter, sworn to or affirmed by the person and mailed by certified mail, return receipt requested, that:
(i) States that the person named in the citation was not operating the vehicle at the time of the violation; and
(ii) Includes any other corroborating evidence.
(4) (i) If the District Court finds that the person named in the citation was not operating the vehicle at the time of the violation or receives evidence under paragraph (3) of this subsection identifying the person driving the vehicle at the time of the violation, the clerk of the court shall provide to the agency issuing the citation a copy of any evidence substantiating who was operating the vehicle at the time of the violation.
(ii) On receipt of substantiating evidence from the District Court under subparagraph (i) of this paragraph, an agency may issue a citation as provided in subsection (d) of this section to the person who the evidence indicates was operating the vehicle at the time of the violation.