Post-election analysis has offered a reminder that people who professionally opine on television often don’t know the first thing about how own their business works.

Considerable Wednesday-morning quarterbacking since the campaign ended has focused on shifting U.S. demographics, including growth in the Hispanic population, the influence of younger voters, and strong Democratic support from single women. “The demographics are changing. It’s not a traditional America anymore,” Fox News’ Bill O’Reilly said on election night.

Many who had predicted Republican candidate Mitt Romney would oust President Obama sounded surprised by the scope of these trends in the vote’s aftermath. Yet had they been paying attention to TV, they would recognize such patterns have been widely discussed, parsed and strategized over for decades.

Perhaps the signature moment came more than 40 years ago, when then-CBS prez Fred Silverman — responding to pressure from advertisers and the network’s sales force — canceled several homespun hits, like “Green Acres” and “The Beverly Hillbillies,” and replaced them with more urban-oriented fare, led by “All in the Family.”

What came to be known as the “Rural Purge” reflected a shift from the smaller counties that flocked to the Eye network. In focusing on younger viewers and major population centers, CBS — then, as now, the most old-school of the networks — underscored how everyone in TV had to accept the ad-selling premium placed on targeting key demos.

As for Hispanics, one need only to have read press releases touting the performance of Univision or Telemundo — particularly among younger audiences, where it’s not uncommon for those channels to surpass English-language broadcasters — to be aware of the marketing power of Latinos, and their disproportionate growth relative to their cohorts.

On TV ratings firm Nielsen’s website, there’s a study called the Hispanic Market Imperative. As the service reports, “Rapid Latino population growth will persist. Between 2000 and 2011, Hispanics accounted for more than half of the U.S. population increase; in other words, their 10-year increase was slightly greater than that of all other non-Hispanics combined. Hispanics will contribute an even greater share (60% or higher) of all population growth over the next five years.”

The importance of this community has long been evident to TV programmers — particularly in major cities, where local newscasts endeavor to attract Hispanic viewers. Many of these top markets are in California, New York, Texas and Florida — the four states with the largest number of electoral votes, which is coin of the realm in minting new presidents.

The campaign also reflected shifting attitudes on issues like gay marriage, with three states passing marriage-equality legislation and a fourth rejecting a proposal to restrict it. Again, the longterm trend lines have been clear to anyone who pays attention to television — including, apparently, Vice President Joe Biden, who cited “Will & Grace” as a factor in his policy evolution, saying the NBC sitcom “probably did more to educate the American public than almost anybody’s ever done.”

Somehow, this seemed to sneak up on the punditocracy, particularly those emotionally invested in a Republican victory.

The media, obviously, approach demographic trends with different priorities than do political campaigns — eager to transform them into triumphs in terms of profit, not votes.

The advertisers dictating the need to reach younger demographics, however, are forward-looking. Part of their rationale for emphasizing adults under 50 hinges on trying to hook potential customers early, gaining their loyalty for years to come.

Political pundits, by contrast, frequently seem to be thinking no further ahead than the next election, only then — once the outcome is known — pivoting to turn their attention to the following campaign. In addition, the fact that older and white Americans generally vote in higher percentages than younger and minority groups has afforded them disproportionate clout at the ballot box, even as the influence they exercise through TV’s ratings box has dwindled.

Republicans have engaged in various levels of soul-searching since the election, discussing ways to adapt that might expand the party’s appeal and spare them future electoral defeats.

Although conservatives often deride the “liberal media,” if they want a better sense of where the country is — and more significantly, where it’s heading — they might want to begin their homework by watching a bit more TV.