Material inequality has been, and still largely is, ubiquitously accepted as reflecting a natural societal order. Only egalitarian philosophers have seen such inequity itself as a moral evil, and so take umbrage to the popular assumption.
The essence of morality is fairness. Different perspectives consider acts to be moral intrinsically (moral absolutism), or otherwise adjudged in light of intent and/or consequence. Most people, and legalistic thought, consider intent when determining the morality of acts. Accidents are therefore without moral ramifications, whereas acts which intended to harm, but failed (and thereby of no consequence), are treated as criminal.
Because a market economy is considered by many to be a natural order without inherent intent to harm, commercial acts are commonly construed as moral; only attempted transactions which egregiously violate fairness are considered iniquitous, such as price-gouging. So, even though capitalism may inevitably deliver gross inequity, and by dint of consequence be unjust, few see the market system as immoral per se.
The love of money is the root of all evil. ~ I Timothy 6:10, The Bible (often cited, but never really paid any attention)
Inequality has never been eliminated in any society. So-called “communism” was a scam sold by ruthless revolutionaries to gullible plebs, who invariably were oppressed in the aftermath of the liberation from the previous regime. Any leveling that went on in the Soviet Union, China, or North Korea was barbaric, not civilized. The same applies to the supposed egalitarian spasm known as the French Revolution.
Individuals’ life chances are predictable. There seems to be an inescapable inherited substrate, looking suspiciously like social class, that underlies life outcomes. ~ Scottish American economist Gregory Clark