King Charles walked around the garden half an hour after his head was chopped off.
instead of
King Charles walked around the garden, half an hour after his head was chopped off.
I think most of the time it's just plain lazyness.
Then again it does seem these days that the emphasis in schools is upon knowledge learning and competition at the expense of grammar punctuation and spelling.
Have you noticed that the word "text" is frequently used to mean the past tense ?
eg. "I TEXT him last week but he didn't reply" ..aaagh !