its because you have applied them wrong.
To apply the stickers get a bowl of soapy warm water... immerse the sticker (without backing) and then apply to window... then with a dry cloth or tisshue rub out the bubbles.
I used a squeegee to rub the bubbles out.. but you can also use a credit card and gently rub out the air pockets but you need to be gentle not to scratch the black ink off.