In Michigan, a speeding ticket is a civil infraction, not a criminal offense, so the legal standard is preponderance of the evidence, not beyond a reasonable doubt, as the slide deck says. I suspect it's the same in California.
Wait a minute, if that's true won't it imply that traffic violations/infractions convictions get you a criminal record ?
Yes. Infractions are crimes so yes. For the most part, they are not treated as crimes. You cannot be jailed based on an infraction. Most job applications I've seen typically explicitly exclude requiring information about past infraction violations.