Having lived in Tokyo long enough to have witnessed crime (with blood on the pavement), reported crime to the police, have people admit their minor criminal behaviour to me, and also hear second hand reports of serous criminal behaviour of people I know, I would limit the time I leave a high end laptop unattended in a busy Starbucks to the time it takes to order a refill/snack or go to the toilet :-) in fact I’ve done it probably hundreds of times. Which is to say I have no real concerns about crime there, but am no idealist. I would not leave a laptop unattended in my own country for any amount of time, the culture of westerners is far more opportunistic for even minor individual gain, and much less conscious of one’s place in society.