A five-minute taxi ride cost a Shanghai man more than the fare when he traveled from Xinchang Road in Huangpu district to Taixing Road in Jing'an district last week. The man, surnamed Yan, allegedly left, or lost, his mobile phone in the cab. When he rang the number, the power had already been switched off.

Yan reported the loss to the taxi company and was told that the driver hadn't noticed the missing phone. The driver confirmed he had picked up another passenger after Yan, but had no idea whether this person had taken the phone.

For whatever reason, Yan insisted the driver had stolen his phone.

The cabbie vehemently denied this. And because both men stuck to their version of events, it was impossible to decide who was telling the truth. In similar disputes (including "indirect" travel routes) taxi companies sometimes refer to invoice records, roadside surveillance systems on roads or GPS records to try to resolve the issues.

Yan told local media that he believed cameras installed in cabs would also be a help in settling such disputes. He said that if a mislaid item was stolen from a taxi, a camera would capture the culprit in the act.

Even the Shanghai Municipal Transport and Port Authority admitted that in 2011 alone they dealt with 330 cases in which taxi drivers were found to have overcharged customers (up 93 percent year-on-year) - although they did not confirm if all of these drivers were affiliated to officially-regulated firms. The authority added that they had apprehended 546 illegally operated cabs in Shanghai, an increase of 64 percent on the previous year.

But although some disputes are resolved, many are not.

One local taxi company recently reported that they received nearly 2,000 calls last year reporting missing items, but that only 480 such items were successfully recovered. About 30 percent of reported missing items are mobile phones, which are easily mislaid when people get in and out of taxis.

Whatever its merits, taxi companies are now mulling over the idea of installing cameras in taxis and I, for one, think this would be a good move. I believe it could provide clear-cut evidence of guilt in cases of theft, or even more serious crimes.

Last week, a local cabbie, surnamed He, was attacked by a man with a knife who refused to pay the fare. Luckily, He was only slightly injured. I believe that if cabs had cameras, similar would-be assailants would think twice before committing such crimes.

Many Shanghai drivers already install their own recording equipment in their cabs in order to protect themselves from false allegations of theft or misconduct.

What's more, transport authorities in Nanjing, Jiangsu Province have fitted more than 9,000 taxis with cameras and audio-recording equipment in a bid to resolve, and hopefully prevent, future conflicts.