Why? That is what they're called. Would you rather have all of us just call them Ctenolucius hujeta all the time? If we did that then most people wouldn't even know what we're talking about. BTW, electric eels are actually knife fish, so do you also expect everyone to start calling them electric knife fish?

In that case, what would we do about spiny eels, which aren't true eels, just call them all by their scientific names? Come to think of it, a few of them don't even have scientific names yet (the borneo python eel for example) so what should we call them?