How is checklist updated? How is this related to low voter turnout?

We heard reports on election day of "voters" who had died but were still on the checklist. Checklist has three categories: current/active, inactive, deleted. Here's how the checklist is updated:

Margaret Poirier, for the Board of Registration of Voters, checks Free Press death notices and Board of Health records routinely and updates the checklist, moving people who have died to the deleted category. In addition, every 2 years she mails out postcards to people who have not voted in 4 consecutive general elections to ask if they want to remain current on the checklist. If they reply yes, they remain current. If they do not reply, they are moved to the inactive category.  *[Needs to be confirmed -- conflicting information. There's a "challenge letter" that is sent out by the state. Don't know who sends the postcard.]

If people register in another town/state, the voter registration office there sends notice to our Clerk and Margaret moves the name to deleted category. If a person fails to inform the new registration town office that they are previously registered elsewhere, they would remain on our active list until the postcard is unanswered (moved to inactive category) or they notify our Clerk (moved to deleted category).

It is logical to conclude that the Burlington checklist is inflated, and at least 10 years outdated at any given time. For example, people who were in town during the last presidential election may have registered here to vote, and are either here no longer, or have no interest in Town Meeting or statewide elections. So we must not feel guilty about our low voter turnout, especially in wards where there is a high transient population. People are to be praised for registering, even if only to vote in a presidential election in Burlington one time!