Wouldn't they find a title most efficiently by 'Best match' ?

Best Match, and all the other sort orders, are just that - sort orders. What makes one more efficient than another depends on the criteria the searcher finds most suitable; if they are looking for the lowest overall price, then price plus postage lowest first would be the most efficient sort order. Other refinements, as mentioned above, also make an individual search most efficient. 

The search engine, however, is - while it is supposed to be influenced by buyer habits - beyond the control of both buyer and seller, and can make any search order less efficient by excluding relevant items and including irrelevant items, and the search engine is what is causing these anomalies, not sort orders.