Legal Question in Traffic Law in California

It's not like TV or the movies. Just getting arrested doesn't mean they have to read you your Miranda rights. Those are only required if you are "in custody" (arrested or the equivalent of it) and being interrogated. Typically, a "detention" such as a traffic stop does not rise to being "in custody" so no Miranda warnings are required. If there was a Miranda violation, the remedy is to exclude the statement, but it doesn't necessarily invalidate the entire case.