In an MLB game, whenever a "pull-happy" left handed batter (a powerful batter who usually pulls the ball, that is, hits it to the right side) comes to the plate, the infielders often put on "the shift" - the shortstop moves over to the right side of the infield, and the third baseman moves to about where the shortstop usually plays. This makes it easier for the infielders to field a hard hit, pulled ball. However, many have remarked that these hitters could easily beat the shift by bunting the ball down the third base line. I know that this is easier said than down, but I would imagine that a professional hitter would be able to do this fairly easily with a little practice, so why is it almost never even attempted?
First off, left handed power hitters do, sometimes, bunt against the shift. Not frequently, but they do; I saw Jim Thome lay down a neat bunt several years back.
However, the reason you don't see it all the time, is because the folks who the shift works against aren't trying to hit singles. They're pull hitters (that's why the shift works), and they're pull hitters because that's the easiest way to hit a home run.
Most "full shift" hitters are on the "Three True Outcome" spectrum; meaning, they're usually going to either strike out, walk, or hit a home run. The really good ones - let's say someone like 2007 or 2009 Prince Fielder - are slugging .600+ (meaning their average trip to the plate, not counting walks, yields 0.6 bases). Even the moderately okay ones are slugging .450-.500, meaning their average trip to the plate yields probably 0.5 or a bit more bases (if you add walks to the mix).
So the question is, if they bunt away from the shift, will they stand on first base over half the time?
I suspect the answer is no, unless they put in a lot of practice. Any practice going into bunting is coming out of their main purpose (slugging), so suggesting that they put in a substantial amount of practice is likely to be a non-starter.
Bunting is quite a bit harder than it looks. Pitchers put in quite a few hours of practice per week on bunting, in the NL, and sacrifice bunts work okay, but not so frequently that I'd consider it easy. You also have a very specific need here: bunting fair, but fairly close in down the third base line hard enough the pitcher can't easily field it (and of course the catcher can't either). It's hard enough to sacrifice bunt (where the only requirement is that the ball go a few feet from the plate and not directly to the pitcher, with a runner who's got a lead and is probably faster on the basepaths); getting that bunt down is quite difficult.
Even good bunters only get a bunt in fair territory around half the time; and of course some of those bunts are outs (ones too close to the pitcher or catcher, which go the wrong way, or are popped up). So half the time, the first attempt will be a strike - meaning he won't have the surprise opportunity at that point.
I would encourage you to read this Fangraphs article, The Truth About Bunting. They did significant work to analyze this exact question, and while they don't come to a concrete conclusion, the discussion might help you understand why you don't see it more.