Nobody in right mind would think that their data is secure. Most people know that unix permissions dont give you real data security and that people can just remove microsd card.

It just means that its nice to have locks in your front door, even if burglar can break the window quite easily. And most people in the world keep their front door closed/locked, even when their houses have windows and they know that people can break in at any time.

But I can be wrong of course, some people might not lock their front doors when they go out.