In Anthony LaPaglia’s new film A Month of Sundays, the latest work from Noise and Felony director Matthew Saville, the 57-year-old actor plays a grumpy Eeyore-like housing broker who walks around in a permanent funk. His character, Frank Mollard, is dour and reserved; a man of few words.

This is in stark contrast to the person who plays him; when we speak, he is at a Bondi hotel having landed just a few hours ago on a flight from LA. LaPaglia is loquacious and engaging, rattling through topics with the kind of straight-shooting, borderline brazen sincerity often associated with beer-infused pub banter (it’s mid-afternoon and we’re drinking coffee).

Perhaps this fair dinkum call-a-spade-a-spade candidness has something to do with his upbringing in Adelaide. Hungry for a more adventurous lifestyle, LaPaglia relocated to America in his early 20s and became – as he described himself to Jon Stewart in 1995 – a “born again New Yorker”.

Like most well-known actors who’ve been working for decades, LaPaglia’s oeuvre means different things to different people. For some, no performance of his will ever equal Joe “I’m the idiot, you’re the screw-up and we’re all losers” Reaves from the flop-cum-cult-sensation Empire Records.

Others recall his stage incarnation of tragic protagonist Eddie Carbone in a late 90s adaptation of Arthur Miller’s A View From the Bridge, which won LaPaglia a Tony Award. There’s also quite a lot of television on his resume, including performances in Frasier (which won him an Emmy) and police procedural drama Without a Trace (which won him a Golden Globe).

But right now acting is not on LaPaglia’s mind; he’s clearly thinking about politics. Our conversation spans Donald Trump: “good or bad, he woke people up,” he says. On a more optimistic note, Bernie Sanders “represents the America I love” but the US election is “turning into a fucking reality TV show, like watching Big Brother”.

On the quality of the GOP Primary debates, LaPaglia saw “idiots talking about penis size, hand size, nothing about policies”. Closer to home, on the subject of Malcolm Turnbull, the actor notes he was in Australia when the current prime minister toppled Tony Abbott. “The whole country seemed to be relieved he took over,” he says. “Holy shit, what happened?”

LaPaglia clearly has no reservations about speaking his mind, so it comes as a slight surprise that he viscerally objects to the culture of famous people using their clout to champion political causes or persuasions.

“I don’t really feel that I have the expertise or knowledge to get out there on the stump or preach a certain philosophy. I feel the same way about the cult of celebrity,” he says. “Why do we ask actors who are sometimes dumb as a brick important questions in our society, and we listen to that? Yet you’ve got a teacher, who’s in charge of the next generation coming up, get under-paid and ignored? Not interesting I guess. You wanna listen to some, what, actor talk about their shit.”

One of LaPaglia’s co-stars in A Month of Sundays is the delightful Julia Blake, probably best-known for multiple performances in 80s Australian soap opera Prisoner. In the film she plays a lovely and caring elderly lady, Sarah, who misdials and talks to Frank over the phone, believing him to be her son.

The two characters strike up an unlikely friendship. Frank embraces her as a sort of surrogate mother figure, whose wisdom and fondness for life inspires him to become a better person. It is rare for an actor of Blake’s age (and gender) to have such a prominent role in any film, Australian or American. LaPaglia believes the situation is getting worse.

“For both sexes it’s become more and more ageist,” he says. “I’ve been told, in my 40s and 50s, that I’m too old to play the father of a 20-year-old. They’ll have some casting where the kid is 20 and the father is, like, 35 in real life. He must have been knocking them out pretty quick.

“It’s the same with seeing older men on screen with women half their age. You don’t often see age-appropriate casting. I think that’s frustrating, for women in particular. But I think it’s frustrating for everybody.”

Almost three decades working in Hollywood (interspersed with a number of performances in Australian films, including highly memorable roles in Lantana and Balibo) has given LaPaglia more than enough time to observe how the top end of town works. The studios’ habit of hiring big-name actors to greenlight major productions is, he reckons, a big reason many films are commercial failures.

“There’s been many big stars who’ve made many big flops, because actually it was the wrong casting,” he says. “When you have big money involved people operate from a place of fear. Nobody wants to be the guy who stood up and said ‘actually, this person’s not as big a star but they’re much better for the film and the film will be better for it.’

“When I started in Hollywood, there were still a reasonable number of people who were concerned with artistic choices. Now the major decision makers are, for the most part, business graduates. They just crunch numbers. They put your name in a computer. They have a whole fucking program.

“They crunch it out and if you’re not worth something in a certain area where they’re getting money from, it doesn’t matter. If you’re lucky, in certain territories – hot in France, hot in England, whatever – and you mean something there, you’ll get the part. It’s a business.”

The Australian film industry, he says, is not all that different. However, “there’s less to lose. Australian movies haven’t reached the point where they spend a hundred million dollars on a film, so the pressure to make the right or wrong decision isn’t quite as heavy.”

According to LaPaglia, A Month of Sundays “cost, like, nothing to make”. He believes audiences, when they are seated in a cinema watching the screen in front of them, don’t actually think about any real difference in budgets or resources.

“Once it goes up on a 40-foot screen, all movies are judged the same. Are they entertaining or not? The budget doesn’t matter,” he says.

“What matters is that when you’re trying to sell the film, to promote a film that cost very little, you have such limited resources to work with. So as an actor you really feel it’s part of your job.”

This is the reason he’s back in Australia: “Acting is one thing. Part of your job after the film is supporting it as much as possible.”

• Join us in Melbourne for our gala screening of A Month of Sundays on 27 April at Cinema Nova in Carlton, hosted by Luke Buckmaster with special guests Steve Biddulph and Matthew Saville. A Month of Sundays is in Australia cinemas from 28 April