Line of Sight in Tabletop Games

 I have very little experience playing tabletop games unless you count Magic, but my possibly incorrect understanding is that in most games involving physical representations of units battling, Line of Sight is a factor. What I'm wondering is whether any boardgame/tabletop game that includes a LoS mechanic has managed to come up with one that is both simple and completely objective. To clarify:

A) By simple I mean it only takes a few seconds to determine whether unit X has LoS on unit Y, it doesn't require any fancy specialized tools, complex math, no rulers, no strings, and no grey area results where its a "close call" on whether LoS is there or not.

By objective I mean that it isn't open to slightly different results, in other words it doesn't involve looking from behind your unit towards the other unit and pretending if you would have LoS in your unit's situation, or whether 26.44% of the unit is visible or anything of that sort.

I'm not criticizing any of these methods or saying "all of these are bad" I'm simply wondering if any game has managed to come up with a LoS mechanic that somehow completely avoids these issues. It seems to me they are unavoidable but with my limited experience I hope I'm mistaken. Thanks for reading, and if you respond with an example game, please be sure to describe how it handles A and B above, since its a sure bet I haven't played the game you are mentioning!