A culture that has ritualized speak with dead in such a way that it is common to speak with one’s ancestors.
Necromancy is otherwise forbidden. The voices of the dead are sacrosanct, but the idea of raising the dead as slaves is repugnant. Raise Dead and Reincarnation spells exist, of course, but remain out of reach for most due to cost and level of magic required.
Crypts and caskets are built in such a way that access to the corpse’s head is easy. For example, people are often “buried” above-ground similar to places that are flood-prone. The style is similar to a sarcophagus, but with an easy to open window near the head.
A lot of work is done to preserve the body, especially the mouth, for as long as possible. Gentle Repose, of course, is used as a ritual. But other non-magical means are available to preserve at least the head and mouth for as long as possible.
Most families with means have at least one person in the family who can cast the spell. Either they have a caster (typically a Bard) or they have magic items that allow it.
The very wealthy may have large crypts dedicated to their ancestors. Middle income families may have about 3-5 they can afford to maintain. The rest are often buried with preserving magics, just in case they are called upon in the future.
The poor may have a single ancestor they can afford to maintain. Some may have access to Gentle Repose and other preserving magics. They otherwise rely on village shaman, clerics, and witches who earn their place among them as Speakers for the Dead.
A new spell that can be cast as a ritual exists which is basically a toned down version of Speak with Dead. It allows the caster to ask a single question, and shares the same 10 day restriction. It’s more commonly used among those who can’t afford the normal spell… usually offered by local shaman and witches.