Have you heard of this little company called BitPay, you might want to Google them. They've accepted zero confirm transaction since 2013 without issue.

We are not discussing theoretical what-if scenarios here. This is real world use of ZCT and evidence Bitcoin functions good enough here for ecommerce.
 
But you've already ignored this, you either aren't even bothering to read replies and just screaming, or are incapable of rudimentary reading comprehension.