Physical bollards are nice if they are applicable to your cirumstances, which for most of us, for most circumstances, they are not. They are also not particularly useful for most types of thefts in the US. Most car-type robberies with cars keyed like the Metris involve smashing wIndows and stealing stuff from inside; bollards don’t really help. They multi-camera security set up I have around the outside and inside of my house (with visible ”No Trespassing; 24-hour Video Surveillance” signs for good measure) help more with that kind of theft.
The Metris does not really need to be guarded against non-tow-away theft. The security devised by Mercedes and implemented on the Metris up to 2020 at least (I don’t know if keyless go is implemented on the refresh; that would be a strike against it) is almost unassailable. You can’t start the car without a key, period. You can’t take the car out of park easily without starting it; in countries where the late-model-used-Mercedes-part-market is more vibrant, when they steal Mercedes equipped with this system but not keyless go, they use dollies to wheel them over to flatbeds. Thieves looking for cars to physically take generally avoid these, or resort to car-jacking.
Keylessgo, on the other hand, can be bypassed with Systems readily available and used by car Thieves everywhere, which is why it is inferior.