Lifevest?

[Jackdaw]

Chances are if a person has reached their teens or adult hood and never learned to swim, the reason most likely is a fear of the water. A person like this would be safer in a standard pfd.
This would give them more piece of mind.

That's simply not true. It has more to do with cultural and family reasons. There are cultures and races with very low swimmer/non-swimmer ratios. Most members are generally comfortable around water (until they fall in over their heads, that is... )