Some of the requirements for submitting a proposal seem questionable, subjective and vague.  How can one define "who" was omitted in a proposal and "what" the proposers "motives" are?

The point of placing a historical marker is to display verifiable historical events and people in those events.  There should be no "motive" for creating such a marker, just an interest in telling the history.  It doesn't matter who submits the proposal as long as the facts are true.  The marker does not need to explain everything about an event or place or person--how could it and still fit on a marker.  The marker can only hit the highlights.  If some other group wishes other facts to be presented, they should have the right to submit their own proposal for a marker and more than one marker should be allowed for any event, location or person.