I read this sentence and it confuses me:
"Consumption of coffee in USA totals in 4 Kg per person."
"USA totals" -- what does it mean?
In the sentence "Consumption of coffee in USA totals 4 Kg per person" (the "in" in " totals in 4 Kg" is superfluous), the subject is "consumption of coffee in [the] USA", and the main verb is "totals". Since "consumption" is singular, the verb is also singular, while USA is plural.
The verb "to total" here means "to amount to" (as Mick already suggested in a comment).
One would normally write, "Consumption of coffee in the USA totals 4kg per person."
Some other examples of the verb "total":
You can also read the sentence as "In the USA, the total consumption of coffee per person is 4kg."
It means that the total consumption of coffee in the U.S. is equal to four kilograms per person.
to total means to amount in number to a specified quantity.
The amount of money I spent on learning English in the past year totals $1,000.
What this example says is that I have spent in total $1,000 on English in the past year.
As for the supposed redundancy of in, you can't total 4 kg per person. You total an amount of something. You need a quantity. 4 kg per person is not exactly a quantity. That's why you need that in there.