Big Little Lies, which begins on Sky Atlantic next week, makes for problematic viewing. Nicole Kidman, Laura Dern and Reese Witherspoon play affluent and variously unhinged mothers who chat, bitch and clash. They may or may not murder someone in upscale Monterey, California, a place of SUVs, anodyne art, sea, coffee and abundant wealth. The New York Times called it “lifestyle pornography”, fixing on that as its saving grace. But the premise is the problem: the wealth is held to be interesting in its own right. Its holders are supposed to fascinate the surrounding mortals; the thinking being that their concerns must be inherently more interesting than similar concerns would be, lower down the income distribution.

It’s the fascination we’re supposed to find in them, ventriloquised on to the minor characters, that is so grating, and what defines “wealth porn” as distinct from “lifestyle porn”. Whereas “lifestyle porn” is looking at someone’s beige carpets and imagining how lush it would feel, “wealth porn” is accepting that someone is more interesting after finding out their net worth.

“I suppose the most trite and obvious observation is that [wealth porn] is a form of escapism, particularly attractive at times when people are facing money pressures in their lives,” says Rowland Atkinson, sociologist and co-author of Domestic Fortress. “But this seems to be different from what we’ve seen in the past. You look at a very opulent production like Brideshead Revisited and that Edwardian era excess had a strong sense of social investment. But [shows like Big Little Lies] present a life that has almost removed itself from society. Staggering wealth now represents the ability to escape, rather than be noticed.” If the drive of wealth in real life is to separate itself, watching it onscreen feels almost clandestine, like watching a thing whose raison d’etre is to be unobservable to the likes of you.

The classics in the genre are the Fifty Shades and Twilight franchises. Christian Grey, or more precisely the entire structure of his sexual magnetism, is his wealth; S&M only works visually if it’s expensive. Shabby surrounds and cheap bondage gear, especially if it’s rusty, look a bit Hannibal Lecter. But there is also a distinctly American underpinning to Grey’s control: part of submitting to him is the inevitability of kneeling to the superpower of his wealth. Try to imagine that relationship working if they had to split a bill, or if he had to get up in the morning and go to a job that he didn’t like.

Jamie Dornan and Dakota Johnson in Fifty Shades Darker. Photograph: Doane Gregory/REX/Shutterstock

More than that, though, there was a segue through the Fifty Shades Of Grey books: the erotic charge of the first novel was transferred wholesale, without any difference in language, pace or intensity, from sex on to money. If the first instalment was genuinely about sex, the rest was about Grey’s stuff (in the book it’s mostly Apple-branded) with the odd helicopter and $500 bikini. Here, wealth porn starts to look like a mould culture grown on actual porn. “The women are kinda average, kinda broke, sexually inexperienced, and this dude just needs you to accept him and take all his money,” noted the US writer Ashley C Ford, who traced this as the through line between Twilight and Fifty Shades.

Clearly, there’s something almost tragic about the idea that money should become its own sexual fantasy. Sam Taylor-Johnson, directing the first film, tried to convey Grey’s billions with his art collection, and noted archly that a number of artists didn’t want to go anywhere near it. “What was really interesting was when I was approaching artists to use their art in Christian Grey’s apartment. It was really polarising in who gave permission and who didn’t,” she said. This being the ultimate artist’s dilemma, whether or not to taint themselves by association with softcore.

Malin Akerman and Damian Lewis in Billions. Photograph: Jeff Neumann/Showtime

James Foley, directing Fifty Shades Darker, has a different wealth porn aesthetic – the more expensive the spaces, the more empty and sterile. There is a symmetry here that is almost too neat, between what wealth now looks like and what Atkinson calls the “crunch point of hyper-consumption”, the moment when you have so much that it all becomes meaningless. The sheer, uncluttered cleanliness of wealth – again, very different from the intricately decorated lives of the wealthy in almost any other given era – conveys at once the desire to sever ties with the complicated world, the quest for elite purity and the urge to forget the excesses of your accumulation.

Sky Atlantic’s Damian Lewis-starring hedge-fund drama Billions, meanwhile, is different because the wealth is on the table as part of the character. That and the fact that, in the show, it’s unlikely one can get super-rich without becoming super-bad. Yet “there is a goldfish bowl element to it,” says Jake Polonsky, its cinematographer. “A huge amount of work goes into the locations. It’s a $100m mansion on the beach, we’re going to take you down and sit you inside it and make you imagine you’re in that life.”

Reese Witherspoon in Big Little Lies. Photograph: HBO

The billionaire aesthetic meets a kind of generalised desire of producers – “it needs to look expensive, it needs to look glossy and it needs to look polished” – and also the demands of the plot. “The truth is that, because the plot is often quite complicated, it’s very important to see and understand what everybody’s saying. That leads us to quite a classical and straightforward style. They don’t want it to look dark and gloomy, which is what I want; I’m a cinematographer.”

It may be that the unstoppable rise of the box set, from time-killer to high art, has partly driven all this: the insistence that it’s no longer the bargain-cousin of the movie industry, that its bona fide good quality has led to the lust for things to look not just expensive but the most expensive. More than that, though, and more than escapism, one wonders if there isn’t an element of gleeful pity in a viewer’s fascination. On paper, we’re interested because the rich have been swelled by their capital, have become larger, more important people. But in fact, in shows such as Big Little Lies, we watch these houses, these beaches where no ordinary feet can tread, and note the anxious emptiness to the plenty, the existential “now what?”, the dust of pointlessness on the gleaming surfaces.

Big Little Lies begins on Monday 13 March, 9pm, Sky Atlantic; Billions is on Tuesdays, 9pm, Sky Atlantic