> Robbers do not routinely detect the presence of cash
But the reverse might not be true.
Just because it is not detectable does not mean people who feel unsafe would carry large quantities of cash.
If I was going into a bad neighborhood, I wouldn't carry a lot of cash.
But in japan, I've seen how people behave differently. for example, I saw a lady leave her purse on a restaurant table while she went to the bathroom. This kind of stuff is common in japan - people feel safe and there is little expectation of theft.
Also, this "cash is unsafe" meme is wild. Robbers do not routinely detect the presence of cash on your person using millimeter wave scanners.