Zeion, snakes are not like mammals. They don't learn how to hunt. They don't forget how to hunt, simply because they've been in captivity. While a snake, released into the wild from captivity, would probably take a while to figure out where the best hiding, sunning, and hunting places were, it would inevitably do just fine. Anyone who's lost a snake in their home can testify to how these animals fare in a strange environment...well enough that we can't locate them, lol.

The hatchlings from the warehouse were wild caught, imported baby burms. Even if they had been captive bred...they were hatchlings. Perfectly equipped to survive in the wild on their own, and perfectly unadapted to captivity as of yet. They were the perfect way to introduce a new species to the environment there.
This is where the vast bulk of the Burm population in Florida came from.

However...it may not necessarily be where the boa, Afrock, retic, etc populations came from. There HAVE been released or escaped pets. Just a lot fewer of them, which is why all the screaming is about Burms, and not about boas.