After yet another late-night host’s role went to a man, executives tell their critics they just can’t get the best women to do the job

US late-night television is routinely pilloried for being too male and too white. Last week, even as Comedy Central announced that biracial South African standup comedian Trevor Noah would replace Jon Stewart on The Daily Show, the battle over TV diversity raged unabated. After a year in which six late-night TV host jobs have gone to men, the clamour for more women on screen has only increased.

But TV executives are now fighting back. They reject the old boys’ club characterisation, arguing that it’s about comedy, not feminism or a rejection of racial diversity, and the success of female comedians in late-night talkshow roles – Chelsea Handler, Amy Schumer, Joan Rivers – serves the point.

“It’s not an old boys’ club but a series of different clubs – the Jimmy Kimmel club, the David Letterman club,” says one network executive. “There’s no executive decision-making that says we need an average white male to fit into the slot. If you’re looking to cast the widest possible net, you’re still probably looking for a white male because it’s a formula that turns off the least amount of your audience.”

Executives say top female stars, such as Tina Fey or Amy Poehler, are unavailable. Both have careers in film and as TV producers, and express little interest in the relatively poorly paid grind of a late-night talkshow. “You’d have to be unhappy to want the job,” another TV writer told the Observer.

However, what may be in large part a ratings and availability decision for TV executives – late-night talk is a rare profit point in a fragmenting industry – is viewed as discriminatory by others.

TV writer and author Nell Scovell, a frequent commentator on the lack of female representation, called The Daily Show announcement “the death of hope for a female late-night host”, a game of chairs that consistently fails to represent either the audience or available talent.

When Scottish host Craig Ferguson stepped down from his 12.30am slot on CBS, he was replaced by British actor James Corden; when David Letterman steps down later this year, another white male – Stephen Colbert – will take his chair. In recent times Jimmy Fallon took over The Tonight Show on NBC; Jimmy Kimmel moved to 11.35pm on ABC and Seth Meyers got NBC’s post-Fallon slot.

Cheryl Wade, a professor at St John’s University school of Law, New York, specialising in race and gender disparities, says that the homogeneity of late-night TV is certainly curious. “As an African-American woman, the implication is of white male supremacy. There are only two possible explanations: discrimination, and a presumption of incompetence when it comes to women and people of colour, or that there really is something wrong with women and people of colour – that they’re not as funny or entertaining.”

The problem of race in the US, said Wade, is that once a person of colour fails or is shown to be inadequate, it taints an entire race. After the 90s black TV host Arsenio Hall, it proved extremely difficult for an African-American to host. “It’s the absolute definition of racism,” Wade said.

People who run late-night TV believe they have evidence the biggest audience comes with a white guy Kamau Bell, comedian

There seems to be room for the failure of white women. “The white men making decisions know there are plenty of talented women because they have wives, mothers and daughters. They have the ability to see beyond the gender of a white woman but that doesn’t necessarily exist for people of colour.”

Wade added: “The inability to value women and people of colour is irrational discrimination. It’s subtle, unconscious and implicit. It does harm to both parties, and decision-makers don’t even recognise it.”

Still, there are glimmers of hope in Noah’s appointment. “You have two choices, two paths to take as a comedian,” he told the Washington Post. “You can tackle the difficult subjects and be harsh about it, be brash, be abrasive. But adding hatred to racism is not going to help everybody. So I like to have fun around it.”

While some media commentators fret about Noah’s “offensive jokes aimed at Jews, at fat women, at Asians, and African-Americans”, most welcome his appointment. And with African-American comedian Larry Wilmore chairing Comedy Central’s The Nightly Show immediately after Noah, there may be room for optimism – at least from the perspective of racial diversity, says Wade. She says the success of Shonda Rhimes, writer and producer behind Grey’s Anatomy, How to Get Away with Murder and Scandal, as well as hip-hop drama-soap Empire – will percolate to late-night TV talk. “These shows have been so successful because African-Americans are so starved for images of people that look like them.”

Others are less optimistic. In a recent essay, late-night TV comedian Kamau Bell noted: “People who run it [late-night TV] believe they have evidence the biggest audience comes with a white guy. And it will probably remain that way.”

And for women? Despite success in the past, they remain mostly confined to morning and daytime slots. Scovell, author with Sheryl Sandberg of Lean In, says she’d even cheer a host being joined by a female sidekick.

“We’re waiting to see when next time becomes this time,” she wrote recently. What could increase the chances of a female late-night host? “Electing a female president. Once a woman proves she can be leader of the free world, maybe another woman will be considered capable of sitting at a desk, chatting with guests.”