The American Automobile Association (AAA)'s application form (mirror) states:
If you intend to drive in the following countries, be sure to check INTER-AMERICAN DRIVING PERMIT box page 1: Brazil and Uruguay.
However, Wikipedia says that this is incorrect and that the International Driving Permit is accepted in Brazil and Uruguay:
Both [Brazil and Uruguay] signed the 1968 Vienna Convention, making them both parties that lawfully recognize IDP.
Furthermore, from my understanding of the AAA's application form, all other countries that accept the Inter-American Driving Permit also accept the International Driving Permit.
This makes me wonder: Is there any point in getting an Inter-American Driving Permit (IADP) instead of an International Driving Permit (IDP)?
Assume that the International Driving Permit is issued in the United States (but I'm curious to know whether IADP has any upside compared to IDPs issued outside of the US as well).