Why do you low elo junglers not get ur jungle item

Depends on if it's an energy champ or not.

A built jungle item usually is weaker than a different item and it's common to build straight into a or because their power spikes are greater than a flat 60 AD with 10% CDR, or a Cinder with no cooldown, or a Echo which is semi garbage.

You don't get less XP for not building it out, and if you don't have mana issues, a core item is more than enough.

There are plenty of junglers that sit on their incomplete jungle item... Even in diamond+ Elo...

You don't need to rush the jg item every game. The jg item is there because the build path is cheap and a lot of times junglers don't have a lot of gold. But if you have gold for more expensive components (which doesn't happen very often unless your team is snowballing) by all means get them.

Everyone should get these:

Not everyone needs these:

Low ELO junglers don't understand how to jungle, let alone build items correctly.