At a traditional burial today, the mourners don’t actually get to see the casket go into the ground. They gather for the dedication of the grave and a short committal ceremony, cry a lot, then stand around to hug and chat. The casket just “hangs out” with some funeral personnel watching over it, and they bury it later.
Many folks don’t like that. They feel strange not to be part of finalizing the burial.
You can arrange with the cemetery to have the casket lowered as part of committal ceremony. It is meaningful when participants can drop, soil, flowers, notes or other items onto the lowered casket, leaving the deceased settled in his or her final resting place rather than hovering above it.