Should've used GPL...
But the network effects are too strong and the GPL requiring the source code for drivers to be released increases the network effects. Unlike permissive licenses.
Busybox is still overwhelmed suing companies repeatably ignoring the GPL.
This large scale deployment is apparently billed by some as the payoff for the promise of microkernels w.r.t. "security" so I guess they just don't mean yours?
Android's toybox emerged when Rob Landley, the main busybox developer, left the busybox project because of the lawsuits.
Toybox uses a BSD license.