Correction:
"We should first invest in mass transit, both to clean our air and save American lives if you really want to defend our freedom" from fear. Every person driving towards you could be an Al Qaeda terrorist chanting "Allah Akbar. Die infidel!!!" just waiting for the precise moment to yank their steering wheel towards you. Ban cars to save lives! ;-)
Yes, I'm joking, but my point is we have greater threats to address at home first.
Few of us expect a fire to break out that we can't handle, or for armed thugs to break down our doors in the middle of the night, so we provide defensive responses for such occurrences, just as we should provide defenses for diseases and injuries that none of us can anticipate. Every other developed nation on Earth does that, but not us.