A seller might prefer a cash offer to an offer contingent on the buyer securing credit (credit might fall through). Or, like landlords, a seller might prefer a buyer with a higher credit score (same reason -- buyer is more likely to be able to secure credit and close the deal). A seller might prefer a slightly lower total offer with a serious amount of "earnest money" over a slightly higher total offer without significant earnest money (buyer might try to back out). A seller might prefer to sell to a family with a nice story in their buyer's letter than someone buying a 2nd or 3rd house. Or the seller may think all offers are too low and they can hold out and get a better offer later.
Real estate transactions are not very straightforward. A seller might accept a lower offer if they feel the buyer is more likely to be able to go through with the transaction or just go through it faster. And sometimes they do just plain like one buyer better.