It does make sense to err a bit on the side of caution for warnings. With warnings, a false positive is better than a false negative. It’s better to occasionally annoy the driver (within reason) than fail to warn for an accident.

This isn’t the case with braking. You want to have a high degree of confidence in that scenario because you don’t want to cause an accident. It’s better to react later to an impending collision than it is to cause an accident that would have never happened.