Some are trivially low, like Florida which is $10k for property damage only or NJ which is $5k property damage only. South Carolina, Virginia, Mississippi and New Hampshire don't require it.
Edit: I am willing to bet there is a strong correlation between the levels of insurance required and the insurance compliance rates. Anecdotally, TX and MN have relatively high minimums (both in the top 10), and they have high non-compliance rates, and MA is in the bottom 30% of states. I don't have access to all the data though.