Right, but they have a lobby, so that will actually be met with resistance. This approach was chosen as it's a quick way to appear that you're doing something to combat car theft without actually meeting a lot of political resistance.

I suspect it does affect the manufacturers indirectly: if you make an insecure car (ahem, Hyundai/Kia), theft rates and insurance premiums rise. That in turn means that residuals (resale values) go down which affects the profitability of leases and reduces demand for new cars, at least until the flaws are fixed.

How about we do both? No reason we cannot punish criminals while also holding lazy manufacturers to account.

Because this is not an easy crime to catch or punish, these cars are so easy to steal a layman can do it in minutes without making much noise, take it to a chop shop, and be off with some money in no time.

Getting better at identifying and shutting down these chop shops is a good idea obviously, but that's also hard. On the other hand, forcing companies who didn't give a shit about security for years to pay for retrofitting the shitty cars they put out is actually a lot easier.

AFAIK, it’s not about emissions or reception, it’s about increasing the LEO coffers via traffic fines.

It may be described as a signals concern but that’s simply window dressing.

Radar detectors usually do emit some radio as a byproduct of how the receiver works. Plus it lets the radar detector companies sell radar detector dectors to the cops. And upgraded radar detectors to the chronic speeders that can detect the dectector detectors. Etc.

Was going to mention Hyundai/Kia.

(Background: many pre-2023 or so Hyundai, Kia, and Genesis models have a catastrophic security flaw that allows thieves to open, start, and drive affected vehicles without needing any access to the key fob at all. This is far worse than a signal cloning or relay attack and has resulted in skyrocketing theft rates and spiralling insurance costs in many countries…)

Depends entirely on the particular attack and the particular implementation. Even rolling code systems have vulnerabilities (e.g. relay attacks), they're just harder to attack.