I think it's because we now have true equality of opportunity. — Hallucinogen
I can point you to a history book - THE COLOR OF LAW (2017) - that will show that we do not have, and have not had equality of opportunity. We need not go back as far as the 18th and 19th centuries and slavery. Let's go back to the 1930s.
IN the middle of the Great Depression, Roosevelt recognized that the availability and quality of housing in the US was poor. Of course, there were fine houses being built, but across the board, housing stock was deteriorating and was in short supply. In 1934 Congress created the Federal Housing Administration (FHA) which was charged with the task of promoting housing construction. One element of the law was that the FHA housing program was NOT TO RESULT IN INTEGRATED HOUSING. Blacks and whites would both be served, but not in the same places.
For white people there was an ambitious program of suburban community creation with tracts of new single-family housing located next to existing cities. For blacks, there was to be a large program of rental housing creation inside existing cities. Before these plans could be rolled out, WWII intervened. After WWII, the FHA program took off.
The quality of the housing was
at least GOOD. The urban rental housing was sturdily built, and where they were maintained, FHA buildings remain in use and are in good shape. The suburban housing tracts were semi-manufactured, and were built very rapidly. Still, the quality was at least good. The houses were fairly small, and were situated on (usually) spacious lots. No city or suburban developer ever had difficulty finding urban renters or eager buyers. The housing was affordable but not "cheap".
Over time, the affordable suburban housing was improved by the owners. Rooms were added, landscaping was carried out, and services were upgraded. The value of the homes has, on average, continually appreciated. Some modest houses built in the 1950s now sell for $300,000 to $400,000.
The rental housing built in cities provided good housing, but renters do not accumulate equity. After 10 years of renting, a family is not better off in terms of equity than they were the day the moved in. Suburban families, however, stood to gain equity which they could either cash out, pass on to children, or keep by remaining in place. When they did cash out their property, they might enjoy a very large windfall that could be used for education, purchasing another house, or some other life enhancement.
Many cities had a weak commitment to maintaining the rental housing stock. If it was allowed to deteriorate, a downward spiral could--and often did--begin, which ended up with the rental housing turning into high-rise slums. Chicago had huge rental housing tracts built which were initially good, but ended up being altogether unlivable--owing to urban housing authority corruption and neglect.
The upshot of the FHA program is this:
After 40 years of official segregation, and 70 years of de facto segregation, suburban whites were much better off financially than they were immediately after WWII, and urban blacks were as bad off, or worse off, than they were in 1946.
Since education is organized along community boundaries, suburban communities have generally funded much better education than poorer cities. That's another way that opportunity is not equally distributed. Poor and poorly educated populations tend to have worse health outcomes than more affluent people. That's a third inequity of opportunity.