I understand it perfectly. What is important is not the energies behind the two pieces of metal relative to each other, it is the balace of personal and public interests and the effectiveness of the means that the public employs to guard thier safety versus the infringement on individual liberty.
Which is more inherently dangerous, a gun or an automobile?
By what justification may a state deny my automobile safety certification because I will not ID myself? (Hint: I am ALWAYS the guy behind the wheel, all the state needs to know is that I am the individual that it has certified)
My toeprint satisfies that.