Visible light is electromagnetic radiation too. Does this mean that an LED is the same thing as an AirTag?

I'm not sure if this specific source is isotropic or directional, but it's very possible for it to be both extremely hard to detect from even a couple of meters away, yet still pose a great hazard.

It was literally lost. A properly engineered beacon cannot be lost this way as long as it operates.

> He said a search vehicle was driving past at 70 kilometres per hour on the Great Northern Highway when a detection device revealed radiation.

They found it because it is literally a beacon.

Beacons do nothing to prevent loss, they only facilitate relocation.

I think the idea would be to have a gieger counter in the vehicle near the pellet that can detect the pellet radiation, and sound an alarm in the vehicle if the pellet radiation is no longer detected, so the driver knows immediately that the pellet has become unsecured.

They found it because they got incredibly lucky.

If it would have bounced just a few meters further off the road, landed in a ditch and get covered by something, or its emission beam angled away from the road/sky (for directional sources), it might never be found (or not before it causes some harm).