I have yet to figure out why people lie to make excuses as to why they did not complete a task. I've had past and current coworkers like that and also past college learning teammates.
My current coworker, Ron, whenever called out on something he did wrong immediately blames somebody else for his actions. "Ron, why didn't you do this?" "Oh because so and so was on the phone and they were supposed to do it." "But Ron, that makes no sense, your initials are next to this!" He is a nice guy, don't get me wrong, but he can't handle anything being HIS fault, ever. He was 5 minutes late swiping in one day and blames somebody on the other side of the door. Strange.
My past teammate from a class I had was insane with her excuses. We had a team paper do every week and I swear she had an excuse 4 weeks in a row as to why she either turned her part in a day late OR didn't turn it in at all. For the first paper, she made the team late by one day, she said, "I had to make an emergency trip across town." The second week she made us late again, "My computer crashed so I will try to use my friend's computer, but oh wait, her Microsoft word isn't working!" Third week she didn't turn her portion in at all, "I had a seizure so I was in the ER all day." Forth time she didn't turn in anything either, "I was waiting for everybody's portion, then fell asleep watching the Superbowl." NICE! She was a keeper.
People, stop making excuses and start taking responsibility for your actions! I mean, if you're an avid procrastinator, then admit it! Don't try to make people believe some crazy ass lie.