On October 31, doorbells will ring across the nation as costumed children fan out from their homes and chant, “Trick or treat.” If their goodie bags are lighter this year, they will offer reminders of the immutable laws of free-market economics ignored by President Biden.

PayPal projects that candy will cost 34 percent more than last year. While the Bureau of Labor Statistics pegs the figure at a smaller 13.1 percent increase, that’s still the largest yearly jump the Consumer Price Index has ever recorded, and outpaces the total rise between 1997 and 2006.

Because of more expensive ingredients, higher fuel costs, and supply chain hiccups, since summer it has been looking like the Grinch would expand his portfolio and suck the fun out of October 31. Hershey Company warned, as Reuters reported on July 28, that “it would fall short of meeting demand for the all-important Halloween and Christmas holiday seasons.”

If the Biden administration was aware of the nation’s struggling Willy Wonkas, it didn’t step in to “fix” things, which was for the best. Hershey and its competitors managed to pull out a win without subsidies, regulations, or executive orders, and according to the National Retail Federation, Americans will spend about $3 billion on the sweet stuff.  

Consider, by contrast, the Baby Formula Famine, still lingering despite White House efforts. The shortage was created when the FDA shut down the Abbott’s Sturgis factory in Michigan, fearing contaminants. When none were found, the regulators made no haste to open the spigot because they had no incentive to do so.

Bureaucrats get paid whether they cause a problem, fix it, or do nothing at all. Halloween, however, accounts for 10 percent of Hershey’s annual sales. Heads would roll had those ghosts and goblins gone wanting, so they had to act fast to increase supply or suffer the consequences.

This is the laissez-faire economic policies of President Reagan demonstrating their timeless wisdom, while Mr. Biden’s top-down, command-and-control system — not to mention inflationary big spending — has been unequal to the task of reducing the pain felt everywhere from the gasoline pump to trick-or-treating.

It’s a lesson that will be tossed into those Halloween sacks along with the bounty of sweets that America’s capitalist system makes possible, while children promised socialist utopias by Venezuela, North Korea, and other Marxist regimes endure starvation as a matter of course.

Socialists rise to power by promising candy for all, saying they’ll take from the children with full sacks and distribute it with greater fairness — never mind if some children have walked all over the neighborhood while others sat at home watching Nickelodeon.

In a 1977 radio address, Reagan cited a letter written to him by a Minnesota high school sophomore, Paul A. Leonard, that demonstrated how Reaganomics would go on to whip inflation in the ’80s — delivering prosperity and opportunity — while today, Mr. Biden struggles to keep basic staples on the shelves.

Mr. Leonard recruited 15 students for an experiment where they’d receive candy in exchange for pushups. On day one, he tried a socialist system. Doing five pushups earned a piece of candy, and the total number was then divided by 15, ensuring equal shares regardless of individual efforts.

This resulted in an average of 16.2 pushups, amounting to three pieces of candy per student. In the capitalist experiment that followed, the five-to-one ratio remained the same, but there was no collectivism. “In other words,” Reagan said, “there was an incentive for each one to do his or her very best.”

Under these guidelines, productivity rose 30 percent and seven students completed the maximum of 30 pushups, almost double the four who’d accomplished the feat under the socialist scheme. They had demonstrated, in Reagan’s words, “the difference between the magic of the free-market system and the idiocy of Karl Marx.”

The superheroes and SpongeBobs going door-to-door on Monday will be seeking chocolate and candy corn, not lessons on economics. But adults can use the holiday as a teachable moment, educating children that their treats are the result of capitalism, and unmasking the ghouls who seek to trick them with the siren song of socialism that has a bitter taste indeed.