It appears there are brazen thieves in every country. A couple of years ago, I posted a YouTube video taken in NYC of a group of thieves in a stolen panel truck. They cut the stanchions of a bike rack with a gas powered saw and stole 6 bikes, all still locked to the rack. the whole thing took less than 5 minutes. All this was done in plain sight of at least a dozen witnesses. Many took pics & video but no one intervened.
When multiple thieves are involved, a single individual stands little chance of preventing the theft and would risk personal injury. IMO, Recording as much information as possible and notifying law enforcement is the best approach.
There have been incidents however, where a group of citizens banded together to confront and restrain a thief until the police arrive. I wouldn't hesitate to join such a group.