I don't disagree with your sentiment in the last paragraphs about enforcing existing codes and worrying about developers not being held accountable, but to ignore that some land use choices generate more stormwater run off and other externalities than others, seems short sighted to me. I also like to point out, that the residential structures, may have been built prior to the current building/zoning codes being made and hence may have been grandfathered in. I don't know the history of how building codes evolved in Newark so that is only educated guess on my part. Additionally, in 2018, Newark's Office of Sustainability had established some programs regarding stormwater runoff. One of them was a catch basin adoption program and another was a rain barrel giveaway, while the City hasn't seemed to follow up on these efforts, their decision to run these programs indicates to me that this issue isn't purely seen in the way you describe. Additionally, the NJDEP's Resilient NJ for Northeastern NJ, also looks at variety of strategy to mitigate flooding issues from the micro to the macro level. While there are plenty of big ticket items suggested in various scenarios, plenty was written on the importance of small scale action.