Lol! The average coffin weighs a lot, just by itself.
Usually, a church has several stairs to descend before reaching the sidewalk.
Too bad there isn’t some kind of Conveyor Belt to set the coffin on top of, press a button and transfer the coffin to the waiting vehicle. There is probably some ancient tradition that pallbearer are based on. Today, it’s seen mainly as a last honorific gesture to one’s true amigos.