Well, speaking directly out of my ass:
1) There are a lot less of them. Tight-knit, insular communities with fewer members to look after benefit from a "guerilla effect" wherein their slow-building success is harder to identify and stamp out. Considering how universities treated Jews in the early 20th century, I don't doubt that greater steps would have been taken to "box out" the higher education ambitions of Asian immigrants if the degree to which they would fill Ivies and UC schools today was known in the 70s and 80s
1b) Smaller communities foreign to American values (or at least conditioned by circumstance to value frugality) would have been insulated somewhat from the very American pressure to engage in ostentatious displays of wealth, that long-time Americans would not have been.
2) Save for one infamous exception, their successful neighborhoods and businesses weren't razed by government order (Sorry, George). Tulsa is of course the example du jour, but the much more banal "municipality running an overpass or freeway directly through the black quarter" played out dozens of times across the country as the ISHS was constructed, and there are many instances of the aforementioned "urban renewal" initiatives deeming perfectly stable black neighborhoods "blighted" in preparation for leveling them (and the businesses they contained). In comparison, most Chinatowns, Koreatowns, and Japantowns still exist in some form.
3) A significant portion of the black population didn't "start from zero," but from less than zero. The sharecropping system and mass incarceration in the South meant that the ability of many black men and families to build personal wealth was heavily curtailed by a debt regime structured specifically to keep them from investing in property, businesses, and even their own education. This is still ongoing via contemporary debt, for which black Americans broadly face worse terms (a situation which lenders are unable to explain, despite settling or losing a number of massive discrimination lawsuits).
4) The Asian experience of racism and colonialism is fundamentally different from the black experience because it didn't involve a generations-long campaign of dehumanization, which was necessary to justify race-based slavery in a Christian country. This means that anti-Asian racism is generally rooted in xenophobia and echoed in American culture socially rather than institutionally; anti-black racism, however, is deeply rooted both in social customs and policy and is aimed at directly controlling the movement and agency of black Americans.
All that said... There is a group of black Americans that don't suffer from much of the baggage that families who have been here since before the Civil War contend with. In many ways, the experience of African and Caribbean immigrants in America is more akin to that of Asian immigrants. Coincidentally, their educational outcomes are also phenomenal, and by some measures better than that of Asian immigrants. (It should also be noted here that Asian immigrants are not a monolith and that the experiences of immigrants of Chinese, Indian, Japanese, Korean, Filipino, Pacific Islander, or other descent are not necessarily the same, re: experiences with colonialism, time in country, etc.)