> assuming the chances of the rocket debris landing on a particular country is likely single digits a year if at all that is, what's the point of a fine

It’s not likely, but debris may land on top of humans, and may be large and not only physically, but also chemically dangerous.

As to that fine, https://en.wikipedia.org/wiki/Outer_Space_Treaty doesn’t mention that, but does say:

“States shall be liable for damage caused by their space objects”