There really is a reason as to why they seem rude, although some might not be. It's usually because these people look after you. They want to get you to your home safely. They want to protect you in any danger, so when you talk loudly, or even silently, it loses their focus, making them lose their temper, because these people go to house to house, dropping you off, driving, dropping you off, driving, and cycle repeats. You should honestly feel thankful for your bus drivers, because you would be walking ten thousand steps home if you didnt.