As developers, I think our collective definition of "junior" and "senior" is very different than in most professions.
In other industries (think electricians, welders, doctors, attorneys, etc) you'd still be very "junior" if you only had 3 years experience.
And my theory is that a lot of HR and Executive folks are trained to think that way; they just haven't bought into our way of seeing things...and they don't necessarily appreciate how quickly things change in this industry; and how quickly people can up their skill-set to senior levels.