There are just as many A320s out there as 737-800... there are many more 737NG variants than the 800's combined, yet there are no news reports of cracked windscreens on anything but the 7378 and 787.
Plenty of Airbus cracked windscreens documented here:
http://www.caa.co.uk/docs/1357/F0001519ReplyLetter.pdf