Conceptually the flaw is treating cash as a proxy for value.
Consider the assertion “Cash is one important piece of the puzzle. The impact may be limited without other resources like health care and child care.” This is paradoxically spot-on in highlighting that money in of itself doesn’t create value, people create value for one another. Taking people out of an underperforming value stream by injecting cash is like confusing palliative and restorative care. Pain meds can keep a person limping along, and it is great as a bridge to get to a cure, but long term use has risks.
As an alternative, I would advocate for a government (or other org) facilitation of people strengthening the streams of value between themselves. This doesn’t rule out a cash distribution based on increased taxes, but would focus more on enlisting community cooperation.
One might look at wealthy people as tax cows to be milked or as people who have insights into how value is created. Instead of creating an adversarial relationship of tax avoidance, create a mutually beneficial relationship of opportunities to give and serve.
The most successful wealthy people serve large orgs in boards of directors. What if there was a similar set of local boards that guided a grant or a loan program for life transformation in the way that student loans or GI Bill works but with an explicit stipulation (as opposed to the implicit stipulation of education) of how the funding would be used to create a better life well after the funding is complete?