It needs to grow over decades organically for the people to get used to the idea and the institutions, for example, like in Hong-Kong. Singapore is another example and they yet don't have completely open democracy.
The ground must be fertile, as they say in allegorical terms, for democracy to take root. You can't impose it and then wish it to work and have it work. You can't throw money at it (as AF has shown us). It's a messy process. Sometimes, like Panama, you have the right accidents happen and it works --but at least then they could rely on the legacy of Marti (as they were part of Columbia during independence from Spain) and they had the US administer the Canal Zone till '00, I believe.