I haven’t looked but my guess is the foreclosing lender was probably the 1st TD holder. Thus, they were senior to possible other liens on the property, which were wiped out when it reverted to the beneficiary at the time of the trustee’s sale.
Not so for a bidder. Their Trustee’s Deed would have been junior to any other existing liens and thus the property was too encumbered to make it worth bidding on at the trustee’s sale.