> the outcomes of post-British colonies are incredible
By what metric? Recall that not all people value the same things.
The outcome of British colonialism in Tasmania was 100% extinction of locals - I mean sure, you can call that incredible as you did, but that was never a word used by Truganini
Jamaica, sure, greatest Winter Olympic team ever .. but hardly the poster child for colonialism and impossible to claim as "better off" than sans or alt colonialism.
Uganda, well, ... enough said.
We can likely agree that the expanding British Empire had a tremendous eye for real estate, resources, and location. The bulk of places colonised by the British had plenty of potential for exploitation and exploited they largely were.
The arc of such colonies once the sun set and the Empire retracted was varied, the lucky ones were able to reclaim local control of their own resources and relations, a good many were largely stripped and left to flounder locked into ongoing situations not of their making.
I’d say India has done really well, and that’s partly in credit to the British. A lot of the infrastructure that India used to succeed was inherited from the Raj, such as a professional Army that has never interfered in politics, a competent Civil Service, a Parliamentary style system where minorities have had a reasonable say.
Most important of all, and directly attributable to British influence was getting rid of princely states that owed their allegiance to the British crown. Britain made it clear that they would not accept independent states and every princely state would have to accede to India or Pakistan.
Britain really tried to help India (and Pakistan) succeed. The blame for some of the failures and mistakes can’t be attributed to the British (Indian economic policy before 1991, Pakistani policy towards Bengali speakers), but they deserve partial credit for the political and economic success of India.
People who aren’t Indian can’t understand how remarkable it is that India has stayed united and functional. Even Indians who haven’t lived outside India underestimate it. Indians have diversity within similar to Europe, but the country remains united. A big part of that is that the current Indian state is a successor to the British Raj, which in turn was a successor to the Mughal Raj. The longer India is ruled from Delhi, the more normal it feels.
This unity is the source of Indian success. Without it India would resemble Africa more than Europe. More resources would have been wasted fighting wars within India and all of India would still be struggling with poverty, famine and starvation instead of manufacturing iPhones.
People often caricature this argument by saying sO wHaT iF tHeY bUiLt RaIlWaYs. The Railways don’t matter, they could have been built earlier or later. But once a polity fractures and blood has been spilt, there’s no fixing that.