good to know that it was your general frustration and not a response to any member / post.
There are ways that many other boards deploy to minimize spammers activities e.g. limited access for new members etc. Anyway dont intend to get in to that discussion.
But in the absence of such measures, IMHO current moderation speed is good enough. Also I personally don't necessarily agree that boards suffer due to minor delays in taking care of such spammers.
In terms of volunteers I am sure there is stringent criteria to be able to be considered for the job. I haven't seen that being published. Neither have I seen any thread soliciting new moderators or providing job spec. Therefore, I would be surprised if there are any applications for the job.
And even if there was such an advert I wont expect many to qualify / apply. That's how most boards work and perhaps most societies work.