Smartphones are arguable exposed to theft risk in more scenarios than laptops are, and the security on a smartphone is generally weaker than on a laptop (at least one with whole-disk encryption).
At the end of the day, as you said, phones are easier lost and stolen, but there is barely a difference now in the functionality of security between a phone, laptop, and desktop; they're all the same. Now, for convenience, many users don't bother having a password on their phone. That's not functionality though, that's just how a user has decided to protect their phone's content...
