Roger is a thief, but he is very young. At the beginning of the story, he tries to steal Mrs. Jones’ purse, but cannot lift it when he tries to snatch it and run away. He steals (and tries to steal from Mrs. Jones) because he is poor.
Rogers’ family is not there for him, which is why he has to fend for himself in the streets, and which is also why he relies on stealing from people. He does not only steal for food and shelter to survive, but also for personal desires. He tells Mrs. Jones that he was going to steal her purse to buy a pair of shoes. After he gets caught and taken back to Mrs. Jones apartment, he has the opportunity to steal again and get away, but because she treats him kindly, he does not.
How story relates to contemporary times
In modern times, stealing is still a problem for many people. People steal for multiple reasons, such as the things they need to get by, or, like the story, to get things that they do not necessarily need, but want.
When Mrs. Jones treats Roger kindly, he has the chance to steal the money again, but decides not to, because she trusts him not to. If you give someone freedom to make decisions on their own, they decide for the better most of the time. When people are limited off from something, restricted, even if it’s for their own good, they feel the need to do what they are not allowed out of curiousity or other reasons in order to not take their opportunities for granted.