Multi-column forms create usability issues
- users omit to notice some fields
- fill out the wrong fields out of confusion
And actually, Shopify implemented this, their checkout form is a single column (except for the name fields and the country / state / zip).
Their second column has a summary, discount code, subtotal, shipping, and total… and a different background color.
There are exceptions to this: credit card details, city, state, and ZIP fields. I’m not mentioning the Name field because it should be a single Full Name field, instead of First Name and Last Name.