If you were thinking of taking your kids to see Last Christmas, a festive romcom written by Emma Thompson, you may want to think again. And not just because of the universally bad reviews.

The film’s Australian classification of PG, or parental guidance for under 15-year-olds, doesn’t give you a clue as to its content, apart from that it’s “mild in impact”.

It doesn’t tell you the film has sexual references and coarse language (“I will nail you to my dick”). It doesn’t tell you a main character dies and there is some violence. Never mind that it will probably bore the under 10s.

With the flood of streaming services joining Netflix and offering movies, and a growing range of movies, games and apps aimed at children, more than 75% of Australian parents of young children say the PG category is too broad for them to make choices about what their kids should watch. And 88% of them think a more explicitly age-based system would be more useful.

An age-based system uses classification categories such as G, 5+, 9+, 12+, 16+ and 18+, and includes adding legal force to the categories from 12+ up. Under the current classification system PG and M, or mature, have no legal force and are “advisory’” only. Mature accompanied or MA15+ is legally restricted but can be watched by a child under 15 if accompanied by an adult.

Complicating matters, while broadcast television and movies are subject to regulation by the Australian Communications and Media Authority, Netflix and other digital platforms are not.

The M classification is not without its problems for children either, because superhero movies are often promoted to kids through merchandise aimed at much younger kids.

The figures about what parents want come from a national survey conducted by the Australian Council on Children and the Media last month, and will form the basis of a submission to the impending review of the classification system by the federal government, which was one of the recommendations of the ACCC digital platforms report.

The ACCC digital platforms report recommended a “nationally-uniform classification scheme to classify or restrict access to content consistently across different delivery formats”.

“I took my children (aged 4 and 7) to see Dumbo which was fine but then took them to see A Dog’s Journey, which was also classified PG, and had to walk out half way through the movie,” one parent told the ACCM survey.

“It is completely inappropriate for children that age (drug and alcohol use, aggressive teenage relationships, car accidents) and that was only in the half of the movie I saw. How can they both have the same classification?”

The ACCC also recommended streamlining the classification system so all the platforms can be treated the same whether movies, free-to-air, catch-up TV or streaming.

“The problem with the PG classification for Last Christmas and other PG movies is it’s too wide,” the ACCM president Prof Elizabeth Handsley told Guardian Australia.

“It’s imprecise at both ends because Last Christmas is fine for 13 and above but not suitable for under 10. Many parents think PG means it’s OK for an eight-year-old.”

Handsley says the ACCM survey of 623 parents told them that the classification system is next to useless because it’s not based on age ranges, and doesn’t give clear advice about what content is suitable for different ages.

“The results sent a very strong message about how people were feeling,” Handsley said. “We know that they want information about age suitability basically.

“They also want detailed information about what makes the movie scary because some children for example are really scared of clowns.

“The government has just relaunched their classification website but it’s still very limited.”

The ACCM believes the Netherlands model, the Kijkwijzer system, which is based on child development, is the gold standard Australia should emulate.

Handsley says there is a well-documented body of research that identifies the types of content that can disturb, scare, or in other ways cause harm to children, at different stages of their lives, and that’s what should be made available to Australian parents.

In lieu of Australia’s weak classification system, the ACCM has been providing Know Before You Go movie reviews for 17 years, which are written by professional reviewers, and more recently the Know Before You Load app reviews. They are receiving 30,000 hits a month.

The reviews provide the granular detail for a movie, which may include plot, substances used, nudity, violence, product placement and positive messages.

Handsley says the reviews on the ACCM website help when a parent is deciding whether a 13-year-old can handle low level violence which might be too confronting to a seven year old.

But the website is limping along via private donations after the South Australian government withdrew funding in July.

It’s been seven years since the Australian Law Reform Commission’s report found that the current classification framework is “highly fragmented, with different guidelines and regulatory arrangements for different media platforms” and that the “costs and regulatory burden of the current classification framework align poorly to community standards and expectations”.

The media landscape has changed dramatically since then and the government has indicated a willingness to hold another review.

“The submission from the Australian Council on Children and the Media proposes a close consideration of how a nationally-uniform content classification scheme would fit within the National Classification Scheme and advocates for an overhaul of the existing classification scheme to include age-based categories,” the ACCC said in its final report.”

ACCM membership includes all the major public, independent and early education organisations, the Australian Education Union, the Parenting Research Centre, the Council of Mothers’ Union in Australia, the NSW Parents Council, the South Australian Primary Principals Association, and other state-based organisations and individuals.