Why do some dog owners not pick up after their dogs?

I would appreciate your insights and comments on the following topic.

I am a master’s student in my final year, and I am currently working on my graduation project. My project focuses on how we can better share the city with our dogs. One issue that particularly needs attention is why some dog owners do not pick up after their dogs.

• Is this due to economic reasons?
• A lack of concern for hygiene or discomfort with the act itself? If so, why choose to raise a dog in the first place?
• Could it be a lack of awareness or consideration for others?…

I would be very grateful for your thoughts and perspectives on this matter.