Short sale in Arizona? Why do some banks want them and others don't.

So in my pursuit to gaining as much knowledge as I can about the short sale process I have turned up an interesting point of view from a lender. I do not want to give details but wanted to make a comment about it so all other agent may be aware of this.

I have a listing, priced comps and listed it right about where it should have been listed. After over 3-4 months on the market, we received an offer at 89% list price. It is not in a desirable area and buyers are scarce. After getting all the way through the process I get word back from the lender saying we needed to come up in price by 227%. Yes that is correct 227% higher. I disputed the value and spent my time completing a BPO for the lender. I submit this to them and the lender says they will take a look at it. My BPO was right where it should be and in-line with the sales price under contract. They get back to us with a new number of adjusting the offer price up by 177%. The contact then states per Freddie they will use the valuation from the contact they have. No room for disputing this. I am trying to get the BPO so I can verify what comps were used and how this value come about. This home has a tenant in it and is set to be sold at trustee sale in a few days.

I have after a long time and a lot of hours discovered the bank had made a mistake. The BPO was 10k less than mine and they are approving the deal. I saved the home from the auction and we are beginning the closing process.