They did not want to create a new "keyword" that would possibly conflict with some existing variable name. So try() is a built-in function, similar to len(), and if you already have a variable named "try" (or "len") then it shadows the built-in (takes priority in that scope).

It's mentioned in the design doc under "Properties of the proposed design": https://go.googlesource.com/proposal/+/master/design/32437-t...

One possible reason is that funcall semantics will probably change (Go 2 is likely to have generics), and so simple funcalls keep the language orthogonal; new operators are forever.