Earlier quoted context omitted.
Non technical users do some things that we don't even dream about doing, like setting auto-lock to "Never". EDIT: I see some people got offended with the bit about Non-Technical users and downvoted me to Hades. I apologize. Not everyone is paranoid like me.
I am technical, and I have no phone security (screen lock). I am sure that professional hackers can more easily steal my credentials remotely (phishing, etc) than from physical possession of my phone. That said, I understand why most people want to use a phone screen lock. I am sure this post will be downvoted.
You're betting on the fact that there will never be an event where a malicious party comes in contact with your phone. Which might very likely be the case, but it's not a non-existent risk.
A phone screen lock is a low friction, low cost solution for mitigating that small but impactful risk.
