Since rationalizations are usually employed to repair cognitive dissonance, and cognitive dissonance is strongest when image preservation is necessary, one hypothesis would simply be that these people have self-images that don’t need much preserving.
Possible test: do these people have an unusually high tolerance for situations and/or self-disclosures that most people would find shameful, humiliating or embarrassing? This might explain a lack of need to rationalize, regardless of the reason for the high tolerance. (For example, we should expect sociopaths to not see any need to rationalize their actions to themselves.]
[Edit to add: not to imply that any of the people in your experiences are sociopaths; just noting that it’s another situation where somebody would have a low need for self-image preserving rationalizations.)
Since rationalizations are usually employed to repair cognitive dissonance, and cognitive dissonance is strongest when image preservation is necessary, one hypothesis would simply be that these people have self-images that don’t need much preserving.
Possible test: do these people have an unusually high tolerance for situations and/or self-disclosures that most people would find shameful, humiliating or embarrassing? This might explain a lack of need to rationalize, regardless of the reason for the high tolerance. (For example, we should expect sociopaths to not see any need to rationalize their actions to themselves.]
[Edit to add: not to imply that any of the people in your experiences are sociopaths; just noting that it’s another situation where somebody would have a low need for self-image preserving rationalizations.)