Singular and plural

There don’t seem to be any rules in English about which collective nouns will be treated as singular and which will be treated as plural.  By some arbitrary process, English speakers settle on singular forms for some collective nouns and plural forms for others.  Yesterday’s Andy Capp got me thinking about this:

Of course,  the joke doesn’t make sense- no one says “”I was just wondering how my saving is doing?,” no matter how logical it might be to say such a thing.   

The question that all this raises, of course, is why I read Andy Capp.   To which the answer is, it was in the paper when I was five, and I thought then that the reason it never made me laugh was that I wasn’t sufficiently grown-up for it.  By the time it occurred to me that there might be a different reason, I was in the habit.