In the DR you will see bars on windows and even on doors/balconies regardless if the neighborhood is safe or not. First and foremost, having bars in a cement home is a tradition that goes back to Spain. Nowadays it also serves as a safety measure, but unlike in the USA where bars on windows are slmost always seen in rough neighborhoods, in the DR this is not always the case.
In Spain bars on windows are badically universal, especially in homes and regardless of the security situation, which is mostly very safe.
With that said, there are cement homes in public streets the DR with no bars on windows and doors while most or every house in their neighborhood have bars. You would think if home break ins and theft was an issue there, they wouldn't last much without putting bars on their window, but the don't.
A similar situation happens with gates and the fence/wall surrounding the property. Occasionally there is a house in a public street with no fence and gates while every other house there has them. Why are they able to maintain that when everybody else has gates and a frontal fence? The criminals avoid robbing them despite in a neighborhood where gates, frontal frences, and bars are universal a home without them would be easier to break in? Alas, crime is not the only readon for people to have those things in the DR. Tradition is a major factor too. Plus, many Dominicans feel a house is "naked" without gates and a verja. Again, in Spain gates and verjas are common throughout. Not so much in the USA.