The reluctance of South American nations to consider otherwise overwhelmingly suitable Chinese hardware solutions demonstrates the essentially frivolous character of these nation's armed forces. A navy that would prioritise its self-image as "western" in character over the objective realities of capabilities and budgets is not a navy at all -- it's a yacht club.
Changing what military equipment your country uses is not as simple as turning on and off a light switch, military infrastructure and procurement have many hidden costs beyond the initial inked contract price. Logistics such as creating new supply chains, retrofitting existing infrastructure, essentially retraining not just pilots but ground crew and other auxiliary staff on new systems is very expensive and until very recently Chinese military equipment was basically completely incompatible with Western systems without massive additional military expenditure, and all that is just the realities on the ground.
The political shadow of the US looms large over all of South America, the ongoing-legacy of the Monroe Doctrine in Latin America means the US have constant diplomatic pressure on South American governments to 'toe the line'. Political organizations such as the Lima Group are evidence of America's policies to punish countries that attempt to change American influence and this extends especially in military circles, which are trained and have strong personal ties to the US. Other, more direct responses are outright sanctions. For example the JF-17 deal could fall apart on its own if, for example the 'Countering America's Adversaries Through Sanctions Act' is invoked over the JF-17s Russian based components such as its engine.
