But a gajillion years ago, newspapers and other periodicals in America adopted a convention of leaving off the ‘s for names ending in s, as part of their space-saving efforts (also omitted the serial comma and other things, if you've ever seen an old paper, you know how crammed they were). It's now standard Associated Press style, and used by many periodicals such as Time, daily newspapers, and so on.
How fascinating! I'd always wondered why there was such different usage of the 's.
Interestingly, the folks at the NY Times still use the 's with names ending in s ... but then again, they still use Mr. and Miss/Ms. :-)