Deficiencies aren't often pursued because it doesn't make much financial sense for the lender unless the deficiency is granted as part of the foreclosure process. I believe in most states it's a distinct action after the foreclosure that will cost the lender more money.

So, owner occupant or not, deficiencies aren't often pursued unless the borrower has significant other assets. Lenders are also very aware that unpayable debts can be discharged through bankruptcy.