Prem Kumar of Visa Tutor tells me more about the Public Charge Rule:
Broad application When a US citizen or legal permanent resident sponsors family such as parents, spouse, children, and siblings, all the applicants are subject to public charge criteria. For aging parents, let’s say, it may be difficult to get private health insurance if they’re new to the U.S. The family category makes up the majority of green card applications.
Catch-22 for health insurance The I-944 Form indicates it’s a strong factor to have health insurance or enough assets to pay for “foreseeable medical expenses”. Most foreign applicants, however, don’t have health coverage nor the assets to pay for expenses before they enter the US or begin to work. How can the US government expect them to have health coverage before they become eligible? This confusion is causing many applicants to buy expensive private temporary health coverage (“visitor’s coverage”).
Adjusting status Let’s say you come on a tourist visa, and marry a U.S. national and want to adjust your status to permanent resident. To apply for a visitor visa, you’re not subject to public charge to enter the US. However, if you choose to adjust status, you must apply for a green card under which public charge applies.