Some certifications I’ve taken make you do a full room scan, including using a mirror to see the computer itself if you’re using a laptop, to ensure there is nothing you could cheat with. Normally a human reviews it before they open the test for you. In addition they have you install a browser extension that fails a check if there is more than one monitor along with a host of other items.

These are obviously extreme measures, but it is possible to try and enforce enhanced levels of proctoring. And I’m not saying I like the idea of doing this for all coding interviews, just that I guarantee people would go through with this if it meant a chance to get into big tech.

Occasions where I've written a meaningful amount of code, linearly and not refactored it a dozen times are probably in single digits in a 25 year career. Nobody gets it right first time, every time.

You could ask it to write you bad code and refactor a few times. But, honestly, manually copying that code over and over again is probably educational gold.

Copying text from another screen looks very different from coming up with a solution live. Lots of breaks, erasing, rewritings are all missing when copying.