Some people talk loudly on public transport because they don't realize how loud they are. They might be naturally loud speakers or just really into their conversation. Sometimes, cultural differences also play a role in how loud people speak in public. They might not be aware that their volume is bothering others.

Sometimes, people talk loudly on public transport because they have something urgent or important to discuss. They might need to make a call that can't wait or share important information with someone. In these cases, the urgency of the situation might make them less concerned about their volume.

Some people talk aloud on public transport because they enjoy socializing. They might not mind if others overhear their conversation, or they might even want to include others in it. For some, talking is a way to pass the time during travel, and they might feel more comfortable speaking aloud than texting.