Puerto Rico is generally considered as a game of mostly skill, with very little luck involved. In this regard, it is more like chess or checkers, than the typical board game that uses cards or dice.
The only random factor I know of in Puerto Rico is the fact that the plantation tiles are initially turned face down, and shuffled, then a number of them are turned face up and made available, with redraws from the face down pile as the game progresses. In theory, this could lead to one of each plantation being made available at any given time, but it could also lead to a (random) abundance of some, and an absence of other choices.
What (if any) other random or luck features exist in the game?