“How much is the ice cream?” A simple enough question, featured on a new TV and online advertisement, posed by a man who just wants something cold. A woman behind the counter responds with a smile: “Prices? No, we don’t have those anymore. We have estimates.”

The satirical ad pretends to be a news report highlighting a “trend” in which more retail outlets take up “the hospital pricing method”: substituting estimates for actual prices for the cost of meals, merchandise on store shelves, and clothing. The scene ends with a partially deleted expletive from the ice cream-seeking man.

While the use of estimates in retail settings is imaginary and preposterous, the advertisement is part of an ongoing campaign by the advocacy group Patient Rights Advocate, which contends that some hospitals are still falling short of a law that went into effect in 2021 requiring them to publicly post their prices. Even then, said Cynthia Fisher, the group’s founder and chairperson, too many post estimates rather than exact dollar-and-cent figures.

“People need price certainty,” said Fisher. “Estimates are a way of gaming the people who pay for health care.”

Although government data shows that hospitals’ compliance with price transparency rules has improved, updating the requirements of that law is the focus of a new proposal by the Biden administration, which aims to further standardize the required data, increase its usefulness for consumers, and boost enforcement. Even with all that, however, the goal of exact price tags in every situation is likely to remain elusive.

“We’re closer to that, but we’re not there,” said Gerard Anderson, a professor at the Johns Hopkins Bloomberg School of Public Health, who studies hospital pricing using the data that hospitals have already posted.

The proposed rule is designed to make it easier for consumers to learn in advance exactly what they might owe for nonemergency hospital care — though that was what the original price transparency rules were supposed to do.

Requiring hospitals to post their prices is part of a larger effort to make medical costs less opaque, which could help individual consumers predict their expenses and possibly slow health cost inflation, if it leads employers and insurers to contract with less expensive providers.

But the data files themselves are massive, often hard to find, and complex to decipher.