__________ mucho esta noche.

I answered: "He bebido"

I answered this because:

"The use of El Pretérito Perfecto in Latin America depends on regional variations but in general we can say it's restricted to actions started in the past that continue in the present or are not finished, or recent past actions the speaker wants to emphasise." 

"I drank a lot tonight" seems like a recent past action...

What am I failing to understand here?

There's also this part:

"However, in general most Latin American Spanish speakers don't really observe this difference between El Pretérito Indefinido and El Pretérito Perfecto. Most of Latin America tends to just use El Pretérito Indefinido, while in the Andean region speakers tend to just use El Pretérito Perfecto."

So... I have two contradictory sets of information given to me... which one do I use?