There are several reasons why someone might walk into a transparent glass portion:

1. Lack of awareness: Sometimes, people may not be paying attention to their surroundings and fail to notice a transparent glass portion in their path. This can happen when they are distracted by their thoughts, talking on the phone, or looking at something else.

2. Poor visibility: In certain lighting conditions, such as bright sunlight or low light, it can be difficult to see transparent glass portions clearly. This can lead to accidental collisions when people misjudge the presence of the glass.

3. Glass cleanliness: If the glass is exceptionally clean or free of any visible marks, it can be challenging to distinguish it from an open space. This can cause individuals to walk into the glass, assuming it is an open pathway.

4. Lack of visual cues: Transparent glass portions without any visual cues, such as markings or signs, can be easily overlooked. Without clear indications of the presence of glass, people may unintentionally walk into it.

5. Distorted perception: In some cases, glass can create optical illusions or distortions that make it difficult to accurately perceive its presence. This can happen with certain types of glass or in specific architectural designs.

6. Familiarity with the environment: People who are familiar with a particular environment may become complacent and assume they know the layout well. This can lead to them walking into transparent glass portions that they did not expect or remember.

It is important for architects, designers, and property owners to consider these factors when incorporating transparent glass portions into their structures. Adding visual cues, such as markings or signs, can help prevent accidental collisions and ensure the safety of individuals.