É como se a união européia, ao invés dos 15+10 membros, tivesse só a Alemanha, a Grã-Bretanha, a Finlândia e a Eslováquia. Não, é pior do que isso, porque a renda per capita da "Alemanha" é menor que a média, e ela é 5x o tamanho da "Grã-Bretanha" ao invés de um terço maior.
Ou, nas palavras da The Economist,
Practising integration is harder than talking about it. Mercosur is an odd quartet. Brazil dwarfs its three partners, but is not rich enough to subsidise them nor willing to surrender chunks of sovereignty, as Germany has done to promote European union. Argentina is too small to play the strong sponsoring role of France, and sometimes adopts the wariness of Britain. All four members are prone to economic crises, which they spread to each other, triggering every-country-for-itself reactions. The new generation of leaders may make matters worse. Keen as they are on Mercosur, they are even more eager to expand the state's role in development, which is hard to reconcile with freer trade and uniform rules.
The countries have dealt with their differences by constructing an “imperfect customs union”. The “common external tariff” has 800 exceptions, says Roberto Giannetti da Fonseca, trade director of FIESP, São Paulo's main industry federation. Exporters to Mercosur often pay it twice, once on entry and again at the border with the destination country.
More worrying, the union is getting more imperfect over time. On top of agreed exceptions for cars and sugar, Argentina has recently piled tariffs on Brazilian televisions, shoes and other goods. Brazilian businessmen blame Europe's unwillingness to open its agricultural market in part on Argentina's protectionism. And now Argentina wants automatic safeguards to block spikes in imports.