Four out of five Australians want businesses to invest more in sustainable practices, according to a survey commissioned by the Unilever corporation, owner of Australia’s top-selling tea brand, Lipton.

Rhapsodic images of beaming farm workers tending verdant Kenyan tea fields tug not only at the heart strings but also the purse strings. Beverage advertising used to focus on the warm inner glow a nice hot cuppa gave you from drinking it, now the glow that comes from buying a product that makes the world a better place.

The conglomerate hasn’t delayed in spending up big to spruik the environmental certification of its Black and Yellow label tea brands. But the cute green frog of the Rainforest Alliance logo now displayed prominently on its packaging guarantees that only half of Unilever’s tea as yet comes from tea plantations certified as environmentally sustainable, and that full certification won’t be fully implemented for another six years.

What you’re unlikely to see in Unilever’s lavish advertising are images of its tea operations in Pakistan, where the multinational’s pitch of “sustainabili-tea” must surely leave a bitter taste in the mouths of workers waging a battle against “casual-tea: 100% disposable jobs”.

The National Federation of Food, Beverage and Tobacco Workers of Pakistan accuses Unilever of a race to the bottom in its embrace of outsourcing and contract labour. At the multinational’s sole remaining directly owned and operated Lipton tea factory, in Khanewal, there are 22 permanent workers and more than 700 “temporary” workers hired through contract labour agencies.

The contract workers are paid a basic wage one-third that of the permanent workers, are not entitled to medical or annual leave, and have no surety of an income from one week to the next.

According to the website casualtea.org set up by the International Union of Food, Agricultural, Hotel, Restaurant, Catering, Tobacco and Allied Workers’ Association: “The majority of these workers have worked for more than 10 years at the Khanewal factory, with an average of 15 years and some as long as 30 years. But since they’re not formally employed by Unilever, they are barred from joining a union of Unilever workers and bargaining with Unilever as their employer.”

How ironic, then, that this is Unilever’s biggest tea advertising spend in years – a campaign that, to quote B&T, encourages consumers to “make a better choice with Lipton” by pushing “the environmental impacts of sustainable tea use, the benefits to the workers and the economic advantages”.

The company seems content to exploit a glaring disconnect in green consumer attitudes identified in the survey commissioned from AMR Interactive and Newspoll: that more than two-thirds of Australians associate sustainability only with the environment and less than a third link it to worker welfare.

It’s not just green consumers who are susceptible to this disconnect. This week the environmental directory Green Pages, which touts itself as Australia’s “leading sustainability directory and new source” rather breathlessly echoed Unilever’s spin by telling its readers: “Every cup of Lipton Quality Black carrying the Rainforest Alliance green frog seal is a sip towards a better life for tea farmers, their families and the environment.”

It’s amazing what sort of endorsement a multinational can gain by giving away four “exclusive” Lipton Tea packs valued at $150 each and buying an advertising package valued at $3,500.

This isn’t to say that Rainforest Alliance certification has no merit. It does. But it’s no coincidence that the world’s dominant coffee and tea traders, from Unilever to Kraft Foods, Nestle Nespresso, Lavazza, Japan’s UCC Ueshima Coffee Co, McDonald’s and Australia’s own Gloria Jeans have embraced the New York-based agency as their environmental certifier of choice.

Starbucks and Australia’s Jasper Coffee are among the minority of beverage brands to opt for Fairtrade certification. (In fact Starbucks alone buys 16 per cent of the global Fairtrade coffee supply, though that still accounts for less than 6 per cent of its total coffee purchases.)

Why? The main reason is price: the Rainforest Alliance certification logo is cheaper. The Rainforest Alliance scheme is often referred to as “Fairtrade-lite”: It is mostly applied to large-scale farming estates and aimed squarely at ensuring environmentally sustainable farming practices. It guarantees minimum working conditions (such as a maximum 12-hour day) but no minimum price.

The Fairtrade model, on the other hand, addresses environmental standards but is primarily focused on the economic viability of small-scale farmers and co-operatives. It asks consumers to pay a premium to ensure more money for the producers and their communities, guaranteeing growers a minimum of $US1.21 per pound of coffee beans, and a premium of 50 US cents to $US1 per kilogram of tea. Fairtrade also charges a 2 per cent licensing fee (based on the wholesale commodity price) to use its logo on product packaging. Use of the Rainforest Alliance-certified logo is free.

Most likely the decision has come down to cold-headed business logic: most customers know nothing about different certification standards, and so long as we put a “sustainable” label on our package that looks good they will be satisfied, so let’s choose the cheapest.

Tim Wallace is a sustainability specialist and online media consultant, has authored one book about business sustainability (True Green @ Work: 100 ways to make the environment your business), and runs a website about environmental and social sustainability called ecologicmedia.org.