I haven’t heard of bodies surfacing except in flood zones.
I’ve heard of the wood casket collapsing and a depression forming in the soil, but you can just top it off with more soil and plant grass.
My family cemetery is not in a flood zone, but the state requires a concrete vault. All I want I a pine box and no vault.
I don’t think funeral homes offer the plain pine box. Nope, it’s particle board - tacky, icky, awful. So people upgrade. Most people, anyway, my mother stuck to her guns and bought the particle board coffin for her mother.
Make your own or have someone make it for you. I had seen some beautiful home made pine boxes. If buried within 24 hours you do not have to be embalmed. A vault is required at my families cemetery. I plan doing it the old way with coffin and vault. Buried on my back with my head facing west along with all my other ancestors. So as it says when he comes from the east and the dead shall arise etc. I am just too traditional. I am from the South where Decoration Day is still a thing to attend. Plus the cemetery bears my family name as it was started back in the day.