looks like a US plug tucked away there at the side...why do we need an extra usa adapter for $1 usd then?

its a good question. I actually beleive that you do not need the adapter. look at it:

It looks like it adds a grounding pin, but otherwise serves no purpose (that grounding effect wont transfer to the R1 AFAIK)
That plug does not look like it fits that adaptor.