Low and High Resource Extraction sites have security.
bear in mind, just because they have Security does not immediately state that said security will save your bottom, just when you need it saving.
The best approach is to first scan any ship you have your sights on. Even if it is currently being engaged by security. You must see 'Wanted' in the left-hand ship readout, before you are legally allowed to engage it.
next assess the ship. Is it currently in a fight ? Is the fight with security? How much security?
A small eagle in a fight seems easy prey. Well.. If that is an Elite eagle, it'll turn on you immediately. And an Elite eagle vs a non-ready combat ship/pilot will make a mess of you.
Also bear in mind the actual ships versus your ship. You might be in an Anaconda which turns slow, while up against an agile Vulture. Just because you see a Clipper at 37% health does not mean it is easy prey. For sure, against my Cutter it's the flying dead, but against a newbie pilot or ship, it'll turn the tables very fast.
Also, bear in mind that ships of 'Master' rank and above have engineered modules. And, against non engineered ships, they'll eat you up.
You need Horizons to compete.
Food for thought
Best practise when new, is to allow security to 'soften' the target up, then you sweep in and finish it off and claim the bounty.