Since my son was little, he could hit on both sides. He used to go in the batting cage and jump from side to side between pitches (yeah, showing off). But, in games he always hit on the right.
When he started freshman year of HS, he decided he wanted to try switch hitting. In hindsight this was a mistake. He worked hard on both sides, but I think his right-handed hitting suffered, and left wasn't good enough yet. Anyway he got very few at-bats as a freshman on varsity, and when summer started, and he wasn't doing that well switching, he went back to hitting on the right, and it was better, so he gave up on the left.
Junior year of HS he was hitting pretty well, leading off for his team. Toward the end of the season, he suddenly developed a pain in his back. It hurt only when he was batting, not while pitching, fielding, throwing, etc. We freaked out - heading into his recruiting summer, what if it was a bad injury? Went to the orthopedist, who said it was a spasming muscle, and it was "only" pain, so he could play through it if he wanted. He decided that he was going to hit on the left, which didn't hurt at all. Had an amazing last few games, hit better on the left than he had all year, and became a switch-hitter again, that summer, senior year of HS, and into college. I think he hits better on the left than on the right, I've asked him if he has tried hitting lefty on lefty, but he hasn't - I think partly because he hasn't had much lefty batting practice (but maybe other reasons, I don't know).
For him it wasn't about recruiting so much, it was just that he discovered he hit better on the left. Maybe, as Bob would say, it is his dominant eye, but he also has more power.