Why is there such a large number of unemployed veterans?

I think it is a combination of all. But remember, nothing will be given to us. We have to sell ourselves in order to get what we want.

There simply are just not enough jobs when you factor a returning workforce such as returning Veterans, ETSing Veterans, etc. And the jobs they do have are minimum wage jobs, which you can't survive on if you are paying your own rent, have children, etc. Employers not taking a chance, although the one's that do get a kickback from the Government. They are afraid of Veterans because of the media stories about Military servicemen going crazy and committing acts of violence.

I believe it is some of each point and also, most veterans really don't know how to handle themselves in the interview process; it's not because of lack of ability, it is just a case of lack of knowledge.
You have one chance at a "first impression" that's it...no do-overs.
You have one chance to make a great impression (in this case good is NOT good enough), you MUST stand out.

One of the best ways to prepare is "role-playing", there are some online services that will conduct a "mock" phone or skype interview or perhaps you may be lucky enough to have a "brick&mortar business that offers in-person services.

If you do it at home, on your own, have someone tape the session.
The person you pick as the interviewer must be "serious", no joking around.

Most people don't want to see themselves as others see them but believe me, you can't ask for a more honest or tougher critic than yourself.

What's the saying... "How do you get to Carnegie Hall... Practice, Practice..Practice!

And finally, before you can impress a "total stranger" you must first "impress yourself".