Huh, so vaultguard does, and with no stealth capabilities built into the class whatsoever. Curious; might be one for the Alex (and possibly a houserule replacing Land Surveying with something else in the Vaultguard list for me).
The intent of the proficiency is that any character who takes it gets a bonus to detect sinkholes and similar “natural hazards”. (This is very useful insofar as such hazards are as dangerous as traps!) Characters who can escape detection by remaining motionless, like Explorers, get an additional benefit of +4 to such throws in dungeons.* Although the proficiency is badly written, please understand that it should include Explorers, Dwarven Delvers, Rangers, and new classes made by the Judge that have some sort of hiding ability. At the Judge’s discretion it could also benefit a character wearing an elven cloak.
I’d recommend that you treat the proficiency as follows:
“Land Surveying: The character is an expert at surveying the land around him. With a proficiency throw of 11+, the character can predict dangerous sinkholes, deadfalls, collapses, or rock slides when the character enters the area. In dungeons, an explorer (or other character with similar abilities) with Land Surveying gains a +4 bonus to his throws to escape detection due to his ability to find the best cover.”
*Note that by design some proficiencies are simply more valuable to some classes than others. Thieves and others eligible to backstab get more benefit from Acrobatics proficiency than characters who lack backstab. Classes who can create magic items get more benefit from Magical Engineering than characters who cannot.