for what it's worth here's my 5 amateur pennies, though i do follow the military technology somewhat...
the term 'spotters' is NOT literal rather a general role description of a small ground-based group tasked with obtaining and communicating immediate intelligence on a target and - which is as important - the assessment of the effectiveness of a target destruction. the term takes its origin from the artillery spotters whose job was (and still is) to guide the long-range gunners deprived of seeing their targets directly.
It is very important to stress, that in any sophisticated air force (which the usaf certainly is) the 'spotters' are only one element of a multiplayer intelligence system designed to assess, collect, select, confirm and finally eliminate a target. the other elements include satellites, local surveillance drones, ground and air based radar assets and , yes, old-fashioned human spies.
it is this element - the locals - any air force strives to use for a better targeting. the us seems inferior to the russian bombers in this regard. more specifically, the russians can rely on the syrian govt arab networks on the ground in their own country whilst the americans are lost figuring out which rebel group they can trust...
and very briefly, as far as i know from the open sources, it is incorrect to favour one air-to-ground targeting and guidance method over each other. there are several methods - the gps, laser, cctv, active/passive/semi-active radar, infrared etc - that are each used in different conditions. each has its pluses and minuses...for instance, the laser is notoriously dispersed by the desert dust and sand while cctv (cameras) cant see through objects well or the infrared is too short range etc etc. thus the most sophisticated bombs and missiles (particularly the cruise ones) are employing a multi-level system which gets expensive...i reckon therefore, the us still enjoys a considerable advantage over the russians in the precision guidance weaponry. simply b/c the americans can spend more $$.
but in syria the gap has been shown to shrink very worryingly for the cocky americans.