Ben, my perspective is going to be a little different. As someone who has interviewed others, I would say that the company ask because they are the one offering the job. It is no different than you trying to hire a nanny, or a landscaper, or a contractor. At some point, you want to know if you can afford their services. Let's be real, when someone wants a job, he or she will sometimes say yes to any salary, just to get the job. But as soon as something better comes along, they are gone because they were never really comfortable with the pay. Just keeping it real. I have been there. Companies want to avoid that scenario, and one of the best ways to guard against that is to ask about salary history. For example: Suzy is anxious to be hired, so she happily applied for a job starting at $30,000. Great. But a review of salary history shows she made $42,000 in her last position, and $35,000 before that. Red flag. Most of us don't want to go backwards. There could be good reason (moving to a new area with lower cost of living, more opportunity to grow, etc) but it's an eyebrow raiser for the company, and a good interviewer will ask follow-up questions. Why shouldn't YOU bring up compensation history before an offer is made? Because they want people who care about the job itself more than the exact dollars and cents of a paycheck. It is important to the relationship building, but there is a time and place for everything, and during early interviews is not the time.

I feel if you can get a foot in the door don't matter the pay I had a great interview today an never asked about pay right now I don't care

Ben, I'm going to be brief. Salary history gives the potential employer a view of your job hopping history. If your moves were lateral and resulted in more pay the potential employer knows that for you it's a numbers game. Subconsciously this tells the employer that your first loyalty is to yourself; in my personal opinion, that is exactly where your first loyalty should be. If you show a drop in pay for a more diverse position the employer knows that you have potential in multiple positions in their company and they can pay you less to get you there. Finally, starting pay is not set in stone. The employer is attempting to get off paying the new hire as cheaply as possible and your salary history tells them in advance what that might be. I hope this helps.

That's simple to answers; the employer is interested about salary history only because when you discuss the fact that you make this much they can get you for the same or give you a rash of B.S. and tell you I can't pay that now we will start you here and see how it goes from here ;simple greed!

This is a really interesting question Ben. I'd love to hear what others have to say as well!