I don't think Cirlig understands how cars work...
Ultrasonic Sensors (e.g. 40 kHz) are typically used for low speed Parking Assist / Obstacle Warning. On my Mercedes, they're only activated at 18 kmh or less. Above that speed, they're turned off.
It's because they have fairly short effective range. Ideal for Parking Assist, useless for Automatic Braking.
Ultrasonic would be a very poor choice of technology for Automatic Braking, as it would inherently require something like a 2m diameter dish and sophisticated coding to provide enough system gain and effective range to be even the slightest bit useful for Automatic Braking purposes. Even then, not really.
I'd be surprised if Mazda were so silly as to try to use Ultrasonics to provide control of Automatic Braking functions.
This isn't the only example in this column of Cirlig seemingly being somewhat unfamiliar with how such modern vehicle technology and systems actually work.