The northern country's, Scandinavia, Viking heritage, no discernible invasions and total integration of other cultures that imposed their will, England, a collection of close knit country's that have existed un-tainted by foriegn invasion for nearly a thousand years,. Then we have the Americas, a vast influx of foriegn invaders, firstly the British In, great number, the local indigenous population harried and them all but killed off, and many century's of mass, on a colossal scale, immigration, predominantly at first from Ireland, and then central Europe. The common factor here is a clash of cultures, mind-sets and work ethics.
Africa, where do you start, the British, Germans, Portuguese, Dutch, Spanish etc, the common factor is a racial mix that has evolved a clan mentality, and such is inclined to favour their clansmen over all others, this is prevalent in the formation of organised crime, in all of the industrialised nations, including the middle and far east, and all powerful enough to influence politicians, bankers and the judiciary. Money talks, and controls.
Any 2nd or 3rd world country that has vast mineral resources lends its self to rampart corruption, its a paradox that the gold and diamond rich country's, of central Africa, have the biggest political and economic corruption, and some of the lowest standards of living on the planet.
Where there is wealth in vast quantities, and a piss poor grass roots economy, then the temptation to skim it off the top is dominant. Nigeria anyone.
Russia, as Churchill once said, " A riddle wrapped in a mystery inside an enigma" vast gas and oil wealth,
coal and iron ore in abundance, and now with the fall of its totally controlling communist regime, Quick witted individuals have soaked up its riches, and have morphed from canny businessmen, into somewhat corrupt oligarch, but not all.
China. something of an unknown quantity, as we do hear of corrupt officials being executed and imprisoned, however, there must be vast legions of local area and remote state officials that are skimming it off the top. its human nature. The bigger the country, the bigger the temptation.
Conclusion:- There isn't one, and there is no definitive answer to why some country's are more corrupt, in politics, economic or law enforcement, only that that when opportunity's arise, there will always be individuals, and multi-nationals , that will spot the opening to make a fast buck, pound, yen, rouble, dong, riyal, rupee etc.
I await a more definitive answer, from the more knowledgeable, and vastly better educated than I, members of this august forum.
All of the above is pure conjecture, not to be taken seriously, or in any way belived.....TAXI!
Untainted by foreign invasion, I think the Dutch would like a word with you. And the Scots, and....