I remember getting my Dad's truck stuck when I was a kid and my brother and I had to walk home about 4 miles, at night. Went and pulled it out the next day and spent hours cleaning it up. Ever since then I have a huge amount of respect for mud and haven't gotten anything stuck too bad, knock on wood. There are so many situations where you can just look at the area and know it's not worth the risk.
I have pulled a lot of people out of mud over the years (when homes were being built on our street, I averaged 1-2 contractor vans per week for a while) and the common theme is that it was their first learning experience with mud. I think that until it happens, people just don't get it.