AirTags only work when in range of iDevices. If you crash your drone in the middle of nowhere, you'll never find it, because unless a hiker (with an iPhone, with a data connection) walks past it, it'll never be pinged.
Also, as I discovered, they're not that rugged. One of my stopped working after a 1.5m drop onto concrete, even with the battery replaced. So I could imagine a drone crash could break it.