This seems really bizarre to me and kind of dismisses the entire premise of this subthread.
So we have a particular activity - theft - which we as a society have deemed to be inappropriate and codified the punishment of such behavior into law. The law doesn't prevent such behavior, it merely lays out the punishment if one is caught and convicted which can be seen as a deterrent. However, vehicle theft still happens which leads us to this entire topic.
The suggestion is to impose requirements via law onto companies who make vehicles to prevent this theft; although interestingly enough no legal requirements for the manufacturer of the tool used in the commission of these crimes. The companies complying with such regulations will pass on the cost to the consumer just like the mandated safety features such as back-up cameras and so forth. So in essence we would be punishing all consumers by increasing the cost of a vehicle to prevent an unrelated third party from committing an already illegal act. Of course what is secure changes over time, so what is secure today may not be tomorrow for a variety of reasons. I'm not sure how that fits into the equation.
Keep in mind this is just one aspect of a vehicle out of many. We already have loads of regulations around vehicles from safety features to emission standards. When you say that a buyer presumably expects a lock to be resistant to this sort of attack you are adding to a very long list of things the buyer may or may not actually care enough about to spend their money on it. When do we admit that many, many different groups have convinced legislators to regulate what vehicles the public is allowed to have rather than pretending we are speaking for the consumer?
Please note that I am not saying all laws and regulations are bad, far from it. I do believe that there are no solutions in law, merely trade-offs which I alluded to above. My point here is to question if another law will actually fix the issue and if the knock-on effects are worth it. As a society we tend to pass laws that stay on the books long after we learn how damaging and counter-productive they actually are; e.g. the war on drugs. We also have an uncountable number of laws and regulations on the books; we literally don't know how many there are. So saying the only solution is more laws seems a bit like saying everything is a nail because all I have is a hammer.
You also brought up ethics in relation to manufacturers. I have to ask though, why do they have an ethical responsibility to prevent a bad actor from using a tool to steal their product from their own consumers? I'm having a really, really hard time agreeing with such an ethical responsibility. How much ethical responsibility can we really put onto manufacturers to prevent crime?