Why is crime so high in America?

I am new to your all country. I love America very much. I left Romania to get a better life with my fianc�e in your nation capital DC. I love it very much and that is where my fianc�e was birthed. Well the other day was a special day, so I wanted to take her to a nice eatery in the Capital so I make the reservations and we go. When we get there we see a gang of people there. I know they were a gang cause in Romania the gangs all wear the same clothes with their names on the back and these guys were called Vallette. They look like really bad people that want to hurt me and my fianc�e. But I had made the reservation and we needed to go to the restaurant. One of the bad men came up and told me to give him my keys and he took my car. My fianc�e was not scared but I think she is used to the crime here. But when I called the police about the situation they tell me the do nothing to help me. My fianc�e think it funny that I am so upset about this but in Romania crime isn't to the point that we can not go out to enjoy food and company then get car stolen while you are still watching. So I ask why is crime so bad here in America?