I believe the operator vs identifier questions were resolved in the pitch thread starting roughly here and that it was decided to depend on the first character (i.e. [Edit: I did misunderstand. @adellibovi corrected me farther down.]+a is an operator and a+ is an identifier.) Since that just happened to be what the compiler does already anyway, it didn’t end up requiring any work in the implementation.
It probably should have been mentioned in the proposal though. And @adellibovi can correct me if I got anything wrong in my summary.