I can attest to what others here have said about cars and bike lights.

Without the lights on my trike, auto drivers don't "see" me, and more often than not come close to hitting me. With the lights on, most every driver gives me plenty of room, with the exception of the few inattentive idiots who --in my opinion-- shouldn't even have a licence to drive. seriously, Why is it here in the US we grant driving privileges to kids that can barely walk and chew gum at the same time?

A dollar to a doughnut says this couple didn't have lights on their bikes and would probably be alive had they taken that precaution.