There are many factors behind their crimes, perhaps the greatest influence is a matter of economics. many people are not able to buy food for every day, those who have no money doing crime like stealing robbed even killed others to satisfy their needs.
Can't or won't they? I think you're trying to justify crimes. This is wrong. Most often, criminals want to have easy money and this is the main reason for their illegal actions. It seems to me that the reason of a large number of crimes in liberalization of the legislation. I am confident that any repeat offence should automatically result in life imprisonment. Moreover, the offender needs in prison to earn itself its contents or to die from hunger.