I agree that reflective tape is as good as reflectors, but they do not
meet the legal requirement of reflectors.  A cop may or may not know
that the reflective material works just as well when he pulls you over.
  If you're in an accident and don't have the legally required lighting
devices on your bike, it's not going to go well.  From the stories I've
read on bikeforum, it doesn't matter if you have stuff that's better
than the legal requirement, if the stuff you have doesn't include the
stuff that's specifically what's required.  The other guy's lawyer will
eat you up.

That's why I think it's dangerous to advise people to take off their
reflectors and replace them with tape.  The effectiveness of the tape is
not the question, it's whether they have what the law says they should
have.  Even things that look like reflectors may not meet the legal
definition of reflectors if they are junky and don't have the multiangle
diffusion that DOT approved reflectors have.

I know the lengths to which defending lawyers will go to get parties off
the hook who are totally guilty.  Ten years ago, a friend of mine took
his nephew to his house across the lake from his on a jetski.  On the
way back, it was dusk, no-wake time, so he putted back home across the
lake at an idle.  A rich guy with a half dozen people on his powerboat,
pulling a skier (during no-wake time, remember) ploughed him down and
killed him instantly, leaving his wife of 6 months pregnant with their
first child.  The guy's lawyer tied it up in court for 5 years, and the
guy never served a minute's jail time.  In the end he wound up paying
court costs and that was about it.