Thanks for the link.
It would appear that Google and PayPal express bypass the page.
Also, your shipping options present some high cost options and the "free" shipping does not mention the carrier or how long it will take. I imagine that you do get a lot of people completing the free shipping option as it is a significant savings.
For me, I want the page to appear before they get to the checkout page. That way no one can bypass it. Perhaps I can strip out the guts and move it to my shopping cart page.