Why aren't plants black? 🌿

I think she's misunderstanding evolution. 

Nothing in evolution suggests that a solution will be 'the best solution'. In fact, that would - strangely - usually be bad. Evolution is about 'the first solution that gets you to survival'. Any more than that and unless there's some actual survival benefit, the odds are good that the 'improvement' will actually make it harder for the species to pivot when the next environmental change comes along to put evolutionary pressure on the species.

Evolution is generally all about the quickest, lowest energy fix that elevates a species to survival. (There are jumps where a sudden, large change can happen - see a little later in this comment for an example... but most evolution is small changes.)

In fact, it's not even species.. it's individuals. In any population of a single species, there has to be some genetic diversity. Evolution doesn't *change* individuals (a common misunderstanding), it *selects* individuals based on their ability to survive. The ones that can get a better chance to reproduce and pass on their genes.

If there were a 'best' solution and everyone in a species got it (since by definition, it would have the evolutionary advantage over every other solution that other members of the same species might have), in a few generations, most, if not all members of the species would be using that solution. 

Now, if some change in the environment made that solution a detriment - most of the rest of the population would instantly die out and some totally unexpected restart for the species would happen - assuming it isn't wiped out entirely.

Which isn't good for the species.