[michaelt]

  researchers found that "the overwhelming majority of
  Android devices are not implementing the available
  randomization capabilities built into the Android OS,"
  which makes such Android devices trivial to track.
  [...]
  Apple, meanwhile, introduced MAC address randomization in
  iOS 8, only to break it in iOS 10. [...] its network probe
  broadcasts to include a distinct Information Element (IE),
  data added to Wi-Fi management frames to extend the Wi-Fi
  protocol.

https://www.theregister.co.uk/2017/03/10/mac_address_randomi...