I guess we are discussing slightly different things and I think we also agree.
Certainly during the activity the person driving the car is a driver regardless, but outside of the activity one would unlikely identify a regular person as a driver (and the person would unlikely self-identify as such).
Similarly for writing dear reader in some column that will be read by someone, during that activity the person reading is indeed the reader, but if you ask most persons that read magazines if they are readers I think most would say no, unless they happen to read more than just the odd "Dear Abby"column.
In the end these tags to identify someone or for people to self-identify are greatly arbitrary and its up to each person to choose what they use as definition. I think society in general follows the usage of the terms described by us in the more recent posts, if someone wants to use the term differently in a more specific or less specific way they should be prepared to clear up misunderstandings.