Tom, beware of comparing apples and oranges.

Lunar missions generally gain accuracy because the vehicle is inserted into a stable Lunar orbit, from which a de-orbit manouevre can be conducted very accurately, especially with the relatively nearby ranging and location facilities of Earth.

Mars missions generally go for direct landing from an interplanetary transfer orbit, with only one shot at the landing and less local triangulation (though that situation is beginning to improve with the number of live orbiters still circling the Red planet).

In addition, the Apollo and Surveyor missions had rocket guidance during the landing phase, rather than a more passive landing system, but future Mars missions are beginning to go back to Rocket-guided landing systems after the post-Viking economy era.

A pin-point landing is NOT going to be as simple as the Surveyor/Apollo tie up, but I'm sure it CAN be done, if needed...