> just Fidelity and Vanguard (and S&P themselves) have to do due diligence

You're proposing bankrupting millions of Americans' retirements because Uber didn't follow local taxi rules?

> if $100 billion fines were on the table for companies like uber, that diligence would be priced into the stock and it would be far more effective

Yes. Again, we're re-inventing massive fines.