No, mandating a million dollar coverage or no license.
What's wrong with mandating $1m coverage?
You seem to assume that it is 20x as expensive as $50k minimum coverage.
It isn't. Not even close. I pay $112 for 6 months of coverage at $500k liability per incident, on a European sports car (collision, uninsured, and comp are additional). That is the required max before the umbrella insurance takes over.
You see, the vast majority of claims are at low levels, but motorists should be required to insure against all the harm they may cause.
It will take multi-millions...not a million...and hey, you're mandating limits on freedom again.