Now we’re waiting for another sensor replacement and have to figure out what to do—either install the bracket again, which is yet another cost, or maybe sell our car and get one that doesn’t have this issue. We’ve shelled out a few thousand dollars this past year dealing with it. And Honda seems to be aware of the problem but not willing to fix it. It’s so frustrating.
It's not just Honda's that are falling prey to this type of theft. So ditching Hondas for some other brand will not necessarily protect you from future theft. Any such component, in local black market demand, can and will be stolen.
FACT: radar sensors have to be in a front vehicle mounting location, not obstructed by any metal or chrome plastic pieces in order to work correctly. So far, the only mitigation this forum as seen is the metal cover bracket already shared, which would not deter a pro, but I doubt very much you are being plundered by a pro, more likely some teen or young adult looking for easy spending cash.
Clearly, someone is preying on your neighborhoods vehicles for high value easy to pick motor vehicle components. THAT is your core issue, so blaming Honda for this is kind of deflective in my view. In your case, having this happen 4 times in one year.. tells me there is a thief (could even be somebody in the neighborhood you know) farming your vehicle for parts to sell. If it was not the radar detector, it would probably be something else, like side mirrors, or the wheels, etc.
If it were me, I would have cameras set up to watch my vehicle and record the theft. The face you see on the camera might even be familiar.
In my case, I have after market security systems added to my vehicles, and if you even gently mechanically touch or manipulate the vehicle such as would be required to remove that radar sensor, the alarm system goes off. Would not stop a determined pro, but works great against clumsy amateurs.
Bottom line though: Thieves - If they want parts for easy cash, it is near impossible to prevent it if you park at night on public streets, or in garages with no security and open public access.