Equal Opportunity Vs. Equal Outcome

How many pundits and political candidates have you heard express this sentiment over the years: ‘I believe in equality of opportunity, not of outcome!’?

But wait a minute! If the outcome is usually or always unequal, where’s the evidence that the opportunity is equal?

Saying that a society should worry only about opportunity but not outcome sounds a lot like a scientist wanting to proclaim a theory true without wanting to worry about the findings of experiments that seek to prove it.

What do you think?