plastic bags make up 0.5 percent of landfill sites

Cancer in the human body can be 0.02% and wreak havoc. It's all relative.

The point is, that such a tiny thing so detrimental to the world, why would we still use it if we have alternatives (which we do). My vote is that we, as a people, are just lazy, selfish, and above all, ignorant.

I've been to heaps of beaches on 6 continents - plastic on EVERY one.

How many of bags NEVER made it to a landfill to be counted as the 0.5%?

That's 1/200th of the contents of a landfill. Considering how many different kinds of trash there are, that's actually a lot