I take real offense to this issue for some reason. "Couldn't" makes more sense.
I also really dislike the improper use of Your & You're.
Misuse of Their, There, & They're really chaps my hide too.
It bothers me when people say "Axe" when they mean to say "Ask".
The recent trend in the English language now that involves lazily dropping the letter "S" at the end of words. Baby Daddy, How she move, She hate me, etc.
I read somewhere, I think in a song lyric, where the vapid strumpet who wrote the song actually listed the word "Trynna" when she actually meant to say "Trying To". Ugh. I hate laziness in language.
Also, when people type "Use to" when they really mean "Used to". Same with "Suppose to" instead of "Supposed To".
"If I Could Do it, Anybody Could do it". instead of the proper "If I CAN do it, anybody CAN do it".