Sure, and some places you’ll get mugged over $5 or worse.

But it’s a lot more likely over $5000 right?

Ding ding ding, that's the key. There are some people who will mug you for any amount > $0.00. You can't make crime disappear by lowering the value. As that value drops, though, fewer and fewer people will bother as the risk/reward ratio shifts. You'll still have crimes from people desperately sick with drug addiction who need something, anything, to get more, and they're notoriously bad and risk/reward calculations anyway. You'll have fewer crimes from people who'd otherwise think, hey, let's go out and boost some phones for spending money.