Punch-card voting machines have demonstrated a fatal inadequacy. Never mind that some worked well. That's no longer the point. If banks had had one-hundredth the problem with ATMs that canvassing boards have had with chads, customers would never had stood for it. Florida's most dangerous legacy, however, is the pseudoscientific credence that's been added to the notion that committees can, after the fact, judge the intent of anonymous voters.
Humans are highly complex, and nowhere more so than in their intentions.
We don't always know what we intend. But voting forces us to make simple, often binary choices. Ballots get marked obscurely. Imagine, then, that a particular recount committee thinks it has divined each voter's intent. That's what's meant by scientific validation.