That is just killings against communists. That is not equal to killings under capitalist states.

Injustices such as the Ludlow would not fall under the former as the victims were not communists. They were workers seeking better wages and conditions under a capitalist system.

Where's the word Capitalism in that title?

I don't think OP is concerned about the existence of one particular article, but rather the various systemic biases in what Wikipedia chooses to include or exclude.

"You know you can do this thing yourself right?"

Person does thing

"No you are using biased language and have to use exclusively sources which are known to repeat CIA imperialist propaganda like the Hamas rape hoax on demand."

True. Would be good to try that and see how it is handled

Asking for the help of others who may see this: Could you help in listing major mass killings by capitalist states?

Will mention ones that I can remember now:

USAmerican regime - Kent State Uni massacre, MOVE bombing, BLM protestors murdered for protesting against the racist regime

British colonial regime in India - Jalianwallah Bagh massacre, Wagon massacre, Massacre of tribes in hilly states
If famines are included, then the Bengal famine, Madras famine, Travancore famine etc.

Mass killings in areas like Ireland n all by the British capitalist regime too

South Korean regime - Jeju island, Bodo league massacres and similar mass killings

Mass killings by Nazi Germany

Might I recommend King Leopold's Ghost if you want a straight up history book of the Belgian Congo. No shade against Heart of Darkness, I think that's a worthwhile read; but reading KLG first will give you more context to appreciate HoD. Or maybe read it after, idk, up to you

True.

But there does not seem to be an equivalent page for 'Mass killings in capitalist regimes'

Even if it is documented, does it not show that how it is organised currently has an imbalance, likely from Anti-communist propaganda, things like red scare etc?

So, cannoted be unbiased, right? My focus was on that. There is no unbiased source, but only ones which acknowledge biases and maybe try to ensure that the biases do not affect the quality of the source too much.