A lot of it is nerves driven. They want to look smart, so they just rip through the question even though they probably know better.
(I have been a victim of this myself.)
(I have been a victim of this myself.)
And these clarifications are mostly dumb. If you pass an emoji into my string function I'm okay with it not working. Similarly if you pass in a negative number then that's your own dumb fault if it does something unexpected.
That's how the real world works. You go to the extent that covers 99.99% of cases. If that means it doesn't work in your crazy scenario, well, create a ticket and it'll sit in the backlog until we clean up old tickets.
If a negative number isn't valid input that should be gracefully handled by the program (e.g. by responding with an appropriate error indicating what is valid and/or invalid) instead of doing something unexpected.
I'm not much of a fan of the current state of tech interviews but seeking clarity around validity of input and how to react to invalid input is one aspect that does (or at least should) mimic "real life"