Street lights and cars. We have the technology to adjust street light brightness and color, if we must have them could we at least dim them in the evening and use warmer tones. Helps us, helps the nature.

Ban most of the private car driving and compensate by building tram/train tracks. The noise cars make is just obnoxious.

Also people not caring about the climate change and the environmental impact our culture has. Being comfortable is more important than making the right choices. People are willing to look away from almost anything as long as they don't feel uncomfortable in their private lives.