Will the Supreme Court actually reach the standing issue in King v. Burwell?  Liptak explains (emphasis added):

The central question in the case is whether the Affordable Care Act allows the government to provide tax subsidies to help people buy health insurance in the roughly three dozen states that have decided not to establish the insurance marketplaces known as exchanges.

That is a significant question, but it is not clear who should be allowed to raise it.

As a general matter, of course, subsidies make people better off, not worse. People who are better off are in no position to complain.

But the plaintiffs, all from Virginia, said the subsidies hurt them by making them subject to the health care law's requirement that they buy insurance or pay a penalty. If not for the subsidies, they said, they would have been eligible for a hardship exemption from the penalty.

The appeals court ruled for the administration on the meaning of the law, but it said the plaintiffs had standing to raise the question. "Although it is counterintuitive," the court said, "the tax credits, working in tandem with the act's individual mandate, impose a financial burden on the plaintiffs."

But news reports suggested that some of the plaintiffs were eligible for health care through the Department of Veterans Affairs, meaning they would not be subject to the penalty. Other plaintiffs may be poor enough to qualify for the hardship exemption.

The Obama administration has not challenged the plaintiffs' standing in the Supreme Court. But it is up to the courts, not the parties in a lawsuit, to determine standing.

And in theory, at least, a court should never decide a case unless it has determined that a plaintiff has standing. In legal jargon, standing is so important as to be considered "jurisdictional."

In this case, then, the standing question is "fact bound," and what news reports suggest is not normally how an appellate court gets the facts that form the basis of its decision.  In cases that have been through a full trial, the "facts" on appeal are almost always those found by the trier of fact (trial judge or jury).  In cases where a party's case or defense has been thrown out without a trial, the "facts" are assumed to be the version alleged by the party thrown out.

If the Court is concerned about standing, it could remand for further factual development, but that would mean further delay in a case of great national importance.  It will be interesting to see what the Court does with this.

For those interested in other aspects of the case, Amy Howe has this plain-English explanation at SCOTUSblog.