Wow, what a thread. As a professional tour director who is a huge fan of Death Valley, I always have to shake my head at the people who travel there and think its like Disneyland. it isn't. Death Valley will test your ability to think and react. As well as make you have respect for Mother Nature and her powers to destroy as well as to nourish.
The rangers there usually do good work and I applaud the OP for at least letting the Rangers know you are aware of what you are doing and a good steward of the environment. Compared to 99% of the other asshats out there that just dump whatever they brought out there and leave it on the path. Thinking mother nature will reclaim it.
Having an axle on the side of the road is not the biggest piece of trash I have seen abandoned out there and I have even seen some Rangers trying to find serial numbers to see who owns what they found.
Giving someone grief because :
A) they chose family safety over leaving trash behind
B) Not returning the next day to retrieve said trash
Is so not cool!
Again, Death Valley, even from Las Vegas, is not an easy trek. With unpredictable weather patterns, chances of flash floods and other problems, it is not a skip in the park to do... And again, the Rangers knew it was there and would probably notify them if it wasn't picked up in time. They know it was family and safety first.
As for the people passing by and not stopping... That's a 50/50 call. The thought of being in Death Valley and seeing a car on the side of the road... MMM... there are some holes out there that are unexplained. Yet you know you would not want that to be you as you pass by.
On tour or in private vehicle (now in a jeep) I always carry extra water because I always come across someone who "Just thought we would rive to the visitor center" and they are at Grapevine Canyon with only a small bottle of water. Broken down and starting to hallucinate from dehydration...