One of these crashes involved a firetruck, which unlike a semi-trailer, does not have a large gap underneath it.
That fire truck wasn't crossing the road, it was at the road side, which creates a different situation. The problem with high trailers is, that they very much look like a bridge to a radar. In any case, a proper side bareer can prevent deadly accidents.
If the radar cannot distinguish between a bridge with five meters of clearance and a "bridge"(trailer) with a single meter of clearance, then the radar simply lacks the angular resolution to be effective. It's the same exact issue as it being unable to distinguish objects on the side of the road and objects in the middle of the road.
It's insufficient angular resolution for the application, no matter which way you slice it.
That fire truck wasn't crossing the road, it was at the road side, which creates a different situation. The problem with high trailers is, that they very much look like a bridge to a radar. In any case, a proper side bareer can prevent deadly accidents.