5 point harness in a car w/o roll cage...How to do it?

I've seen people get tickets for having a 5 point harness, while only wearing the lap part. There justification was that the harness wasn't being fully used. Now if they had only the lap part and no shoulder parts in the car no prob. If you have the submarine belt not in use while driving it's a ticket. Just like if you have the automatic shoulder belts that have the manual lap belt you have to use the lap with the shoulder and do your part. I've been waiting for new laws about changing out seat belts/air bags as a mileage/year service parts. Just to make us safer from us. I was hasseled before for not wearing a shoulder belt in my 64 dart. I explained that I put in lap belts as the car had none when it was manufactured, along with a license plate light. And of course he said that he couldn't tell how old the car was from behind. My A$$ I muttered to myself as the car has black plates and looks nowhere near a newer friggin car. Just a reason for asking for license and reg and now proof of current insurance.