Indeed, this is one Go convention that I strongly dislike. Java did have that approach once (HTMLDOMURIReference, XMLIDREF and the likes) but they learned their lesson.
I also dislike "ID" vs "id" (as short for "identity"), but there is some case for it. The below are from Webster's Third New International Dictionary Unabridged.
First, the case for "id":
id abbreviation
1 [Latin idem] the same
Now for "ID"
ID noun, plural ID's or IDs [REVISED] [identification]
1 a : documentation bearing identifying information
And what's the basis of capitalizing D in ID?