Last night's viewing - America on a Plate: the Story of the Diner, BBC4; Money, BBC2

How's this for an idea? You go to America. Go on. Get a nice shiny red car, drive around. Zoom through the streets of Manhattan with the top down, nip south to Nashville. And eat. Lots and lots of hearty American fare. Diner fare. All the while getting paid for it, because this is work – or it is if you're Stephen Smith, the lucky sod. "On my travels I intend to eat nothing but honest-to-God, home-cooked diner chow," said Smith, if not quite with relish then at least a level of sardonic satisfaction. He has something of the Louis Theroux about him only, in this instance, it's hamburgers he's talking about, not crystal meth. He also says chow a lot. At least four times in the space of an hour. That's quite a lot, isn't it? Chow. As in, "cowboy chow". Or politicians on the election trail visiting diners to "negotiate chow." Chow. There we are, four in one paragraph.

Diners are welcoming places, contended Smith in America on a Plate: the Story of the Diner. They're also lonely, sad, desperate, attracting drifters and loners long into the night, fireflies to their neon flames, strip-lit havens where stodgy comfort food is doled up in hefty portions with a side order of pathos. Few depictions capture that spirit quite so accurately as Edward Hopper's Nighthawks, a characteristically stylish depiction of a diner late at night, empty but for three customers and their white-hatted waiter. Smith tried to track down the Nighthawks diner, but to no avail.

Still, it's an interpretation repeated time and time again. The diner as a haven has permeated the work of Norman Rockwell, John Updike, and countless film directors over the decades. Smith interviewed Suzanne Vega, she of "Tom's Diner" fame. Rather awkwardly, he got her to sing to her hit back to him while sitting, sure enough, in the diner where it was written (Tom's Restaurant, as it happens). But the most interesting encounter of the trip, really, came when he met participants of the 1960s sit-ins that marked the Southern civil-rights movements. Deprived the right to sit down and eat at lunch counters across the South (but permitted to shop in the general stores to which they were often attached), African-Americans took to non-violent occupations, entering en masse and quietly sitting at the tables. More often than not, they were greeted with legalised violence by the waiting white men. But occasionally, just occasionally, they got to order a burger.

The idea of going to school and getting a job is the most destructive one in your brain," said Robert Kiyosaki. Not, in fact, a teenage rioter caught in Currys but rather the multi-millionaire author of Rich Dad, Poor Dad, the book that promises to help you Begin Building Your Passive Income. Passive income was the chow of Money. A bit of a buzzword. It's not just Kiyosaki and his equally prosperous wife who were raving on about it. There's Maria, the self-made millionaires who realised her abilities while working as a PA. And there's Marcus and Fredericka who have lots and lots of money but don't like spending it so seem to live in a virtually unfurnished flat (perhaps we'd all be rich if we didn't bother with tables). And there's David and Shirley, who left their jobs in the public sector to teach Kiyosaki's method. They may not have struck gold just yet, but they're doing all right.

Unfortunately, there were plenty of Kiyosaki casualties, too. Like Janice, the wild-eyed devotee who wakes up at dawn every day to chant things like "I am a millionaire" while windmilling her arms. She's not a millionaire. In fact, she's in debt. So are Reese and Sarah, the teenagers who've managed to raise £500 by spending far more than that on convention-centre courses and wealth-management tuition. They're the Poor Dads to Kiyosaki's Rich Dad, I guess. God forbid they go to school and get a job.