The Military Was Ready in Texas and Florida. What Went Wrong in Puerto Rico?

It's due to Puerto Rico's lack of government management and funding. The Puerto Rican government really screwed the pooch years ago when they created a huge deficit and how they're in horrible debt.
They made themselves unattractive for the US federal government to make the island a state. Heck, we see it in congress continuously as Puerto Rico tries to become a state, and they've been denied again and again. The reason why the island hasn't been ratified as a state is because the government is corrupt to the core, and it would cost the US government way too much in funds to help stabilize the infrastructure and create a more american way of life. There's no lobbying from corporations/people there to help change congress' mind about statehood, and the US public doesn't really give a damn about an island in the Caribbean. That's why there wasn't as much support for hurricane prep/recovery as you saw for FL and TX and why the federal government has egg on its face about how we didn't provide enough aid.

We're only seeing backlash now because it's more convenient for the public to blame the federal government for "abandoning" the island, than to actually do something about it. The government is only an example/representation of the people.