Yeah, it's extremely hard to set up a circumstance where the person in behind is not at fault.
If you get hit and get propelled into the car in front of you, it's your fault you hit the car in front of you (although this may vary by state).
If the manual transmission car in front of you shifts into neutral on a hill and slides back into you, it's your fault.
The person behind is usually in control of the space between cars and they are held to be responsible for it. You can possibly make it not their fault if you shift directly into someone's lane at speed right in front of them and then hit the brakes.
If you change a software license, are users of that software bound to the new terms if they don't "update" to the version of the software released with the updated terms?