[NoZebra120vClip]

Checkout pages never offer "cancel" buttons or "back" buttons. They are designed to corral you into the checkout process without recourse to returning to shop around some more.

This is, of course, easily bypassed with browser controls, but I agree that it is a dark pattern which can trap less savvy people into pressing forward, because it seems there's nowhere else to go.

[benatkin]

"Back" has the old anxiety of Confirm Form Resubmission, so a cancel or close button would be better.

[brewdad]

When all else fails, for any site like this, I close the browser tab. If I choose to reopen the site, I'll be back on the home page and my cart may or may not be empty.