The real question should be 'where are all the Hispanics in college baseball?' They are becoming quite predominant in the majors.
That's a very ignorant question. As someone else alluded to, players in the carribean can sign with MLB teams at age 16 (players in the US can too, it just takes a little more juggling, see Bryce Harper). Prior to age 16, most of those players are already in baseball academies set up by MLB teams. They aren't given a traditional education, but they are educated while practicing baseball, etc. No point in recruiting those countries, because you wouldn't be able to get those kids into school anyway.
Cuba and Puerto Rico are different. Cubans play in their pro baseball league and in their national system until it makes sense for them to defect politically. No sense in recruiting there, as the political hurdles would be way too much to overcome. Puerto Rico, being a part of the US but in the Carribean is kind of the best of both worlds. They have baseball academies, but they aren't run by MLB teams, and the players there have to go by US draft rules. Their baseball academies are run more like high schools making them recruitable players. A majority of their top level guys still sign pro out of HS after getting drafted, but there are a lot of schools that recruit the island pretty hard. LSU had a signee from there that ended up going pro.