system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why do planets tend to only have one enviroment?

For example:

Tatooine and Jakku = Desert

Dagobah = Swamp

Kamino = Ocean

Naboo = ~~Lush forest~~ idyllic paradise.

Hoth = Antarctic
There are more examples, I just can't recall their names.
gpt
According to legend many of them were terraformed by the Rakata. It's also worth mentioning that just because the area of the planet our heroes visit consists of only one enviroment doesn't mean the entire planet is the same (although that's usually the case).