If withdrawing is meant to be “undo consent”, how would you make that as easy as the initial “one click to consent”? Would you not have to show a banner on every page view, with a one click option to “withdraw”?

You'll have to go and ask the legislators what they were imagining. Thankfully it's not being interpreted quite as literally. Sometimes pragmatism saves the day.

I assume "withdrawal" is the legal term used for clicking "no" on a cookie banner.

In which case yes, it is the same as refusal in the context of the law being discussed.

Why would you assume that?

Why does a dog bark? It's just in my nature I guess.

When the permission is withdrawn, the other party cannot collect more data. And the existing data that they collected would need to be deleted if the user asks them to. If the withdrawal of permission also involves permissions regarding data storage and processing, it would mean that the company would need to destroy any personal data that they have.