I suspect (hope) that by the time a person is old enough to have a job, they have developed some sort of value system and are at least roughly aware of what that value system is.
A) rarely have a clear view of their values insofar as it aligns to what they do for a career or job. Maybe about X social issue, but rarely about themselves.
B) careers and corporate brainwashing greatly distorts peoples internal view of themselves and their relationship to their work
C) values change continuously throughout life. The people who seem to hold most tightly to a narrow range over a long time tend to be the least introspected.