That seems something that should be criminal. And realistically always asked how many vehicles with this type of material is there around?

The judge should have thrown it out.

Second thing they teach in forensics is that unless I witness the actual event, it is really hard to tie it to a specific person. I can present dozens and dozens of circumstantial evidence which has sufficient weight for a reasonable person to make that inference, but I cannot attest to that.

Judges should do a lot of things. In reality, their quality and knowledge varies greatly.

Any judge worth their salt would prohibit or censor witness testimony making conclusory statements, especially based on circumstantial evidence. This is Evidence 101. Everybody knows the so-called "hearsay" rule, but almost every rule in evidence revolves around one core precept--no evidence is per se conclusive, and the function of testimony of any sort isn't to submit conclusions to the question at issue.

But implying conclusions is exactly what both the defense and prosecutor are working at; they're constantly playing word games, and some judges would certainly be better than others at seeing through the B.S.

Judges are elected in many areas of the US so they're potentially literally some rando in a robe who wants to put "bad guys" in jail, not some master of critical thinking.

Yeah, and the other way you get judges is via appointment. So there's a chance you have a hack that put in because the executive leader likes their politics.