An interesting idea out of this: if self-driving vehicles reduce the collision rate, road vehicles can (for some applications) get much lighter. Part of why cars are so big and heavy is safety (along with optionality for cargo and high speeds over mediocre roads). Shedding the steel safety cage could lead to improved fuel economy, which would result in a tremendous reduction in carbon output if scaled.
I'm guessing this would also make the cars safer to crash into, or be crashed into by, given that passenger cars would continue to be heavier and sturdier.
I wonder if it will take legislation to solve.
There are many reasons to adopt a lighter car. Collision safety isn't one of them, but if that was your only concern you'd be insane to have a car at all.
That's why it's a chicken and egg problem. No one wants to be in a less safe car when there are so many accidents (and deaths from them) every year.
I think people talk a lot about safety, but I don't think that is as primary of a concern as everybody says that it is for them. How many people actually go research and learn about all the cars they are shopping, vs people who just go to a dealership and listen to a salesman and buy what's in their price range?
Most people don't even read the damn owners manual, they don't even know what that big yellow light is (TPMS or CEL) that has been on for months. They won't buy winter tires in the winter, even though you can get a set for like $700. $700 is too much to spend to increase winter safety by a large margin on a $30,000+ car. Hell, people don't even use turn signals. The little stick that is less than 2 inches away from where your hand should be, and you don't even have to take your hands off the wheel to activate it. The problem is you'd have to decide which of your 16 cupholders to put the cup in, then reach way over and put it down before you could signal.
Regardless, safety is still wanted. Just because people don't go over the top doesn't mean they don't want any at all. Having a lighter vs heavier frame would make a significant difference in a collision between regular-style cars and new, lighter ones.
The rest of your comment is attacking a strawman.
At some point in the future, I hope the NHTSA takes in "probability of crash" into their safety ratings for self-driving vehicles. Otherwise the safety bloat in modern cars will stick around. The equivalent of wearing a motorcycle full-face helmet while riding a bicycle.
Make all the delivery vehicles that have no people in them really light first
We can barely get common-sense prison-reform (or anti-surveillance) legislation on the US for fear of being labelled soft on criminals; imagine the terror of being the legislator who made cars less safe (without even winning favour from the auto manufacturers for doing so).
Some people simply need large cars - how are you going to legislate that?
If I routinely carry 9 people, I need a large van. I don't have the option of a lighter car.