[Q] Why Latin American Spanish?

[paigetheoracle]

Why is it that South America has ended up with its own form of Spanish, while Portuguese is untainted in Brazil and other colonized countries seem in the main to have taken on the pure form of the conqueror's tongue? (I'm aware of pidgin but I'm on about the official language spoken).

 

Are there any other examples of this happening around the world, apart from the Japanese stealing Chinese written characters?