Not quite right. The detective did say in a different place that he (and other LEOs) are considered professional witnesses and implied that yes, they will automatically be believed over the defendant who starts off in everyone’s minds as a liar who did something bad to be in that chair (despite technically being presumed innocent until…).
The part about the tape recorder though was a trick he used to get people talking. He’d have it running for a while, and then very obviously turn it off in front of them and and try to get the suspect to just answer a quick question “off the record”. His decpetion though was that the entire interview was still being recorded by the camera and microphone/s built into the room, and that there was no such thing as “off the record”. So his tape recorder was a prop; unnecessary for evidence gathering. Maybe he’d take his little recorder back to his desk and use the tape to make his own notes for convienience (rather than going over the official recordings himself), but he’d use that official recording as evidence if necesary.
I think we are talking about different detectives and different lectures. That’s not what the guy said. He specifically said he does not keeo the tape after he writes up his notes from it.
Yes this guy says he doesn’t keep the tapes after he’s done with them. But it’s for the reasons I gave - he doesn’t detroy all records of the interview before trial because he’s super confident that his word will be taken for fact. He’s also talking about more serious crimes and interviews/interogations… there’s a higher burden of proof there and the transcripts/video of an interview definately is used at trial. But the detective’s duplicate copy of that same interview (which he makes mainly as a diversion or for his own person notes) isn’t the copy they use in court so yeah, he can throw it out because another copy still exists. The defense can also use parts of what is said during interviews for their purposes, so the prosecutors can’t just burn all the tapes 5 minutes after the interview.
But the OP here is talking about traffic ticket-level offences, where there is a low enough burden that the LEO’s word is usually good enough. There’s usually no record of what was actually said or done other then what the officer writes down as having happened.