If you're actually speeding or breaking some other traffic law and a cop pulls you over, you're likely going to get a ticket no matter what you say. The important question when determining how to handle it, then, is whether you are going to take the time and effort to fight the ticket.
If you're busy, have plenty of money, or just generally are inclined to pay the speeding ticket and move on with your life, then refusing to answer the cop is probably suboptimal. Your justification for not confessing is that if you do so, you "have no further defense for the speeding ticket." If you're going to fight the ticket, you're right and I agree with you. If you're not going to fight it, this has no value whatsoever.
If you're not going to fight it, then you shouldn't be optimizing for maintaining the best possible legal defense; rather, you should be optimizing for not getting the ticket in the first place. I believe that for most minor traffic offenses, you're better off confessing (and throwing in a relatable reason if you can pull it off).
Going with the lawyerly response is, in my view, more likely to get you a ticket than going with, "I think you pulled me over because I was speeding, and I want to apologize for that. I just left a first date with a girl who I have a feeling is going to be my future wife and got too excited. It was irresponsible and I should know better." Cops are people too - taking responsibility and making yourself relatable just might get you out of the ticket.
Interesting that they use such an underhanded phrasing, if their intentions are only good. Why not "do you know that your tail light is out?"
They don't need a confession to cite you for speeding. They already know if you were or not.
I've probably been pulled over 8 times in my life and only gotten two tickets. Who knows - this could have to do with my race or my demeanor - but in general I just try to act as honestly and apologetically as possible. I think most police officers are not trying to be jackasses, and the ones that are will ticket you whether or not you "fess up" or not anyway.
(This probably doesn't hold if you are carrying drugs or going 25mph over, but otherwise I don't think it helps to treat these interactions so adversarially)
There's far more on the menu and cops vary wildly in competence and intention.
I prefer the be respectful and say little more than necessary to excuse yourself route, all while keeping hands visible and making no sudden movements.
There's little to be gained by participating in a voluntary interview and prolonging the interaction, with a whole lot to be potentially lost, including your life.
A couple of times in a couple of decades of driving this has gotten me sent on my way with a warning.
Lifehack: How to Get Out of Traffic Tickets!
1. Say no to self-disclosure. 2. NEVER admit knowing you were doing something wrong. 3. Be civil for 5 whole minutes.
Civility is the one social engineering tactic nobody knows about! I've never gotten a ticket in 20+ years of driving and motorcycling despite being pulled over more than a dozen times. Even female officers won't cite me. Take that, pigs! I'll speed past you and kill you all with kindness.
(Works especially well nowadays, since they expect everyone to be asshole provocateurs or aspiring BLM martyrs. It's just a fucking job. They don't want to be there any more than you do.)
It should be stressed that it's not so in every country
The number one rule of talking to cops is don't talk to cops. Don't be an ass but don't say more than you absolutely have to. It may just be a job for them but that doesn't mean their job can't involve ruining your day if they think they can use you to meet their quota - your interests literally don't align.
I barely trust police officers in my own country and those actually need to go through multiple years of formal training before being let loose on society and end up in a world of bureaucratic hurt if they as much as think about pulling out their gun. Incidentally they also don't have to chase after random people for speeding because we have radar cameras for that.
Cop (agitated): "Do you know why I stopped you?"
Me (apologetic, talking fast): "Yep"
Cop: "You're a fucking idiot"
Me: "I agree, that was really stupid"
Cop: "What the fuck were you thinking?"
Me: "I don't know, it was indecision"
[...]
Cop: "When I get back to the station I'm going to write you a huge fucking ticket"
Me: "Fair enough, I deserve it, it was really stupid"
The guy was a plain clothes detective in an unmarked car driving directly behind me and I'd just run a red light quite late, obviously speeding.
I've always found Sydney cops fair and reasonable, but I would never try this in the US.
I never got the ticket.
It's almost guaranteed that the judge will side with the officer barring any concrete evidence to the contrary.
Meanwhile the officer gets to show up to court and still get paid for it.
Most times it won't even reach that point because you'll be offered a lesser fine if you don't contest the charge, which can be way less, and is worth it since you're almost definitely likely to lose.
What a judge will do varies by jurisdiction and judge, but at least where I am they take a very dim view of cops showing up without evidence.
There are exceptions, but as a general rule being honest, polite, and not volunteering additional information is the way to go. After all even if you were going 90 in a 35 you don’t know why he pulled you over. You’re not a mind reader.
Officer: "Do you know why I pulled you over?"
Driver: "Sorry officer, I guess I was just going 5 miles over the speed limit"
And there you just confessed to breaking the law and have no further defense for the speeding ticket. The correct answer is to just politely turn the question back to the officer ("Hi, how can I help you officer").