"National Association of Realtors, a North American real estate agent association" has the copyright use of "Realtor" with that capital R.  I think you, like many people, are confused by that fact.  You can be a realtor and still not be a Realtor (member of the National Association of Realtors), but, of course, you can't be a Realtor without being a realtor.  Obviously, Mr. Bean is a realtor, but not a Realtor.

I'm, however, still a little confused about "Who's on first?"