Yes, I certainly agree it can be quite rude. In some instances, some people may simply be inattentive, but this too poses quite the predicament, seeing that it can result in one impetuously harming or inconveniencing others. In my personal experience, this is less common for me. However, I do have somewhat of a curse of people cutting in lines in front of me, whether they intend to or not-- equally as disrespectful in my opinion.