That's still detection, even if it can't precisely map the edge of the semi while cars are moving by; sometimes what's on screen isn't representative of what actual bounds the car thinks is off-limits, as we can see here[0] where the model of the commercial truck clips the car's model on-screen. He seems to support this theory that the problem is mostly the brain of the car[1], at least regarding how lidar won't help with object detection in general.

0: https://youtu.be/ttvBZtqxlRo?t=630

1: https://twitter.com/greentheonly/status/1497696259473391617?..., and auxiliarily: https://twitter.com/greentheonly/status/1497696259473391617?...