Ouch! I spent my working life playing in soft ground......it's a different tecnique from using a machine on tar-seal. The first things you learn when snigging are: a) start your initial pull as straight as you can, and, b) if you aren't going forward, and you aren't going backward, the only direction you're going is down. So stop digging.
I reckon those towies haven't had much experience in soft going. You can look at those photos and analyze pretty well exactly what happened.
To a large extent those fellas dug their own graves.