There is a 'don't include captcha' in the settings but, apparently, LJ no longer allows this switch to be turned off.
On the up side, the amount of actual spam comments I get has gone WAY down!
I know that there are people who read this journal regularly who do not have LiveJournal accounts. I'm sorry the setup makes it a PIA for you. I'd recommend getting a free LJ account but those are so full of ads these days, I don't even think that's a good option. Sorry.
But thanks for reading and commenting when you do!