So, say for example the world border is set to 30k blocks. Thats 30k blocks in the overworld... AND THE NETHER?!?! So that means that if you travel to the nether world border and set a portal there, you basically die and cant get back to grab your items.

Please have the world border correlate between the Overworld border and the Nether border (1m in Overworld = 8m in Nether) so that if the world border was 30km in the Overworld, it'd be 3750m in the Nether.

(BTW the End doesn't need a border because you cant tp out of the end to a place other than your respawn point