I can think of big lifts off the top of my head from both Spoto and Malanichev that were real grinds. Even the best lifters do it from time to time.
But yea, as has already been mentioned, a lot of times these guys don't grind, even if they're capable of it. I think a big part of it is the fact that, when they compete, they're not always trying to set world records. And if they are, they're not trying to break them by enormous amounts of weight. As has already been mentioned, if, say, Malanichev is capable of lifting 10kg over the current world record squat, and he's on his 3rd attempt, but 10kg over the record would be a grinder and 3kg would not, it seems reasonable enough to take the 3kg over. Aside from that, if one of the strongest lifters in the world is competing but doesn't feel like he can set a WR on that particular day, he may just do enough to win the meet, rather than risk injury for no real reason.