Most of the hair killed with laser stays down, if not all of it. Part of it might come back to say hello after a while, but laser being fairly inexpensive compared to electrolysis, you can just return for a complementary zapping. Or just get the "rising dead" with electro just like the blond ones. My laser contract, although expensive, also includes 90 % off extra face laser sessions, so I'm not afraid.
The main reason it's labeled as "semi-permanent" or "permanent reduction" instead of "permanent removal" is that it doesn't affect all hairs, and some need to be killed with electrolysis.
But regardless, even if you're unlucky and you have a lot of hair that comes back, the part that didn't come back will for sure have cost you less than getting it with electro.
So while only a few lucky ones can get away with laser only, it's also true that only a few unlucky ones will get the most out of electro only. And I'm pretty sure no one with decently dark hair is in this last category.