Upright burial takes up less space. In some cemeteries today and in the past became so crowded, that people were buried in layers and some were dug up and discarded to make room for new dead. I saw a program that explained why the catacombs in Paris with many skulls carefully stored. It seems it was to make room for a housing development in the 19th? century. Yes, cemeteries were crowded even then, mostly in urban areas.
Cremation is what I prefer, less space and cheaper. Now green burials do not appeal to me. Some people donate their bodies to "body farms."