I'm not so smart, so it may be that you're using "proof" in some esoteric sense which I don't comprehend, but if I invited you over to my house to observe my driveway, which you found littered with 50,000 pennies, all of which were facing heads up, would you not test my statement that "I flipped 'em that way at random" by multiplying probabilities to gether to arrive at a vast sum? ---Or, at the very least, estimating where those multiplications would lead you?
And if it was a trillion pennies, would it then, finally, begin to fail as a method of proof (because the number is TOO astronomical)?
For me, it would depend on what you told me as I rolled up to your house. If you said "I flipped 'em all at once, and they all landed heads-up at once, just by random," I might be suspicious. I'd figure the odds of such a random event and probably conclude that you were one lucky guy fellow who I should get to know better ;)
If, however, you said to me "I flipped them a series of times in a way designed to mimic the iterative nature of natural selection in an evolutionary process," why, then I'd say to you "Good show. Nice work - I bet you're surprised by how fast you got them all to land heads-up." And I'd conclude that you were a remarkably thoughtful fellow who I should get to know better. ;)
Evolution is an additive, iterative process. It's not really analogous to flipping a bunch of pennies and crossing your fingers, no matter how much some people would like you to think that.