Ghosts

The lingering dead are those who are destined for a better world than this one, if they are willing to receive it.

They resist moving on for a variety of reasons. None of them rational.

Those whose lives have included insufficient acts of kindness and goodwill to outweight the evil they have done, or who had done nothing but evil, do not linger here after death. Those that manage it, manage only days or hours, never years.

Because they never believed in hope while they were alive, their hopelessness lingers with them after death. They travel into eternal darkness without protest because they lack the imaginatuion to do anything else.

Not forgetting, on death, they have a debt to pay.
And the collector has no patience for lingering debtors.