But police claim the trade is increasingly being run by traffickers using young Southeast Asian women under compulsion, and prostitutes have been accused of increasing the spread of sexually transmitted diseases (STDs) and contributing to violence among the thousands of young men working in isolated communities far from family and friends.
Sex workers reject the claims. They call reports of trafficking hysteria and, supported by STD experts, have produced research showing very low rates of infection and high use of safe-sex practices.
They also claim to be victims of discrimination, and made an exhaustive case for recognition in a submission to the inquiry by the House of Representatives' standing committee on rural affairs into the use of fly-in, fly-out and drive-in, drive-out workforces. The committee has yet to report.
Last year, the federal Government gave the sex workers' association Scarlet Alliance a three-year A$350,000 grant to continue a migrant sex worker project, including a comprehensive information package on visas, their rights, and Australian laws for women of Thai, Chinese and Korean language backgrounds.
But police remain concerned trafficking victims are being forced to service mining's fast turnaround trade.
Inspector Paul Biggin of the Mt Isa police in Queensland told the Australian the state's mining towns were increasingly being confronted with the problem of "women and girls who cannot speak English, or who have a very low level of English, and a very low level of education, who are basically being trafficked for sex from one mining town to the next".
"They are working on a fly-in, fly-out basis, two weeks here, two weeks in the next town and so on; they are being advertised as available in the local newspapers, and they are coerced or threatened into doing it," he said.
Biggin will leave soon on an international study programme on sex trafficking after being awarded the Donald Mackay Churchill Fellowship, established for research into organised crime after the murder of anti-drugs campaigner Donald Mackay in 1977.
Yet there is little evidence so far of sex trafficking. The Australian Institute of Criminology, which has held workshops on trafficking in Western Australia and the Northern Territory with police and other agencies, says there have been relatively few cases.
Researcher Fiona David said that of those uncovered, few matched traditional images of slavery and other trafficking stereotypes: women had not been abducted, held at gunpoint, kept in chains or beaten. But some women from Asia had been lured to Australia by promises of well-paid jobs and instead found a very different life, at times trapped, controlled and exploited through obligations to repay unreasonable debts, threats of violence, isolation, intimidation, detention, or having their travel documents withheld.
Scarlet Alliance said the laws on sex worker migration and trafficking introduced in the past decade had been framed without expert advice, were passed on "hysteria" and were ineffective.
"Australia's anti-trafficking laws have resulted in thousands of raids, resources devoted to surveillance and investigations, but have found very little evidence of trafficking," alliance president Elena Jeffreys said.
Even without trafficking, the fly-in, fly-out sex trade faces growing opposition. Western Australia plans to act through tough new regulations that will prevent prostitutes operating from motels in remote mining towns, clamp down on newspaper advertising, and give police new powers to enter premises.
In Queensland, where women have reportedly been required to sign statements promising not to work from their rooms, motel owners have sought laws giving them the right to refuse accommodation to migrant sex workers.
But in its submission to the parliamentary inquiry, Scarlet Alliance says sex workers are a valid part of the fly-in, fly-out workforce yet are discriminated against in housing, accommodation, laws and licensing regulations.
The alliance says its members suffer from the same personal problems as miners: at least half are married or in de facto relationships and have to leave partners, lovers, dependents, friendships, support systems, families and mentors to work.
It also says that in addition to a recognised role in teaching safe-sex practices, sex workers can help keep mining boom towns peaceful.
"Studies into violence in mining camps show miners fighting because sexual services are scarce," the alliance says.
"Providing optimum conditions for sex workers - eliminating discrimination in housing, accommodation and advertising, resourcing health and sex worker organisations better - would diminish this violence and provide safer environments for [other] fly-in, fly-out workers."
