What Data Can a Thief Get from a Stolen Phone or Laptop?

It's about that most people are worried about malware, but not so much about real life thieves. There are probably millions of students and corporate workers who probably don't protect their data on especially their laptops. Most smartphones have built-in data encryption, but Windows PC's do not. I think MS should offer BitLocker as a standard feature on all versions of Windows and should also promote the use of it more.