Mark it down as another outbreak of Trump Derangement Syndrome: A single Web site reports gossip that the president is more concerned over Amazon than Facebook, and liberal media explode with outrage and race to the defense of the online retailer — one of the most profitable corporations in America.

That prompted the Tweeter-in-Chief to shoot back Thursday and again Saturday, saying, “Unlike others, they pay little or no taxes to state & local governments, use our Postal System as their Delivery Boy (causing tremendous loss to the US), and are putting many thousands of retailers out of business!” and noting that its lobbying staff has ballooned.

President Trump is on one side of an issue? Cue a press stampede to embrace the other side.

Fine: Amazon’s Jeff Bezos owns The Washington Post, which seems to devote half of each day’s paper to Trump-bashing. Also fine for fact-checkers to jump on one Trump claim: The Postal Service actually turns a nice profit on its Amazon deliveries.

But his other points plainly go to real issues. Amazon is helping to devastate brick-and-mortar retail — you have noticed all those empty storefronts even in Manhattan, haven’t you? Malls are dying across the country.

No, it’s not just Amazon. But the company handles 45 percent of all online retail sales, and that’s likely to grow. Toys “R” Us is closing because it initially opted to just sell via Amazon, rather than emphasize its own Web commerce — and it never recovered.

Yes, you can write it all off as the “creative destruction” that free-marketeers praise. But that’s not something that good liberals used to just shrug at. As Victor Davis Hanson notes at National Review, press muckrakers were all over industry “robber barons” over a century ago — leading to the trust-busting presidency of Teddy Roosevelt.

We’re not calling for a breakup of Amazon, mind you. But shouldn’t liberals want federal regulators to at least look at a company that’s become so dominant? Why is there so little media appetite for raking Silicon Valley’s muck?

We’re generally fans of Airbnb, but we notice that most bad press it gets, if you dig down a bit, turns out to be generated by hotel-workers unions or other threatened interests — not by any “entrepreneurial” journalism.

Then again, Facebook’s trouble really exploded only after the left decided that it might be to blame for Trump’s election. (This, when the Obama 2012 campaign won press raves for its exploitation of people’s personal Facebook data.)

But the bias goes deeper, and directly to why Trump won: Most of the media, like all the other heights of modern culture, is studiously “woke” when it comes to race and gender — but deaf and blind about class.

Unlike the muckrakers, most of today’s reporters, editors and scriptwriters really have no idea how the other half lives, and don’t much care — except spottily, in the wake of Trump’s election.

Here we are in the president’s second year, and they still don’t get it.