Having it as a tld makes it clear, since you could easily have brazil.amazon, bolivia.amazon, peru.amazon, etc. That's more hierarchically correct than amazon.com.br, amazon.bo, amazon.pe.
For most people though I don't think it makes a difference, as I don't think DNS hierarchy is well understood by most internet users.
For most people though I don't think it makes a difference, as I don't think DNS hierarchy is well understood by most internet users.