Market forces

Ricky Tse, of the Hong Kong Inbound Tour Operators Association, said the market shapes the payment structure.

For example, although guides are offered HK$400 ($52) to HK$800 a day to supervise tours that originate in Vietnam and Indonesia, they shun them because Southeast Asian tourists spend much less than visitors from the Chinese mainland, meaning the guides earn less in commissions.

Agents in Hong Kong are wary of attracting complaints, so most groups are only taken to duty free stores that offer a commission of about 5 percent, because even one bad review from an unhappy tourist could easily result in the loss of a long-term business partner, according to Tse.

Tse said that unlike their peers in Hong Kong and other parts of Asia, mainland agencies are unconcerned about gaining bad reputations, and continue to partner with Hong Kong operators known for illegal tactics.

"They don't seem to care about complaints," he said.

Liu Simin, deputy secretary-general of the Beijing Tourism Association, said cheap and negative-cost tours remain popular because of an "unhealthy attitude" among tourists, who continue to prefer cheap choices.

"Travel agencies providing cheap tours are taking a big gamble, but so are the tourists," he said.