I thought this too at first, but now I think A.T.M.'s is okay in some editorial circles as a plural non-possessive. It's used in many other NYT articles - as is non-possessive G.I.'s.

"...some writers still pluralize initialisms in this way. Some style guides continue to require such apostrophes - perhaps partly to make it clear that the lower case s is only for pluralization and would not appear in the singular form of the word, for some acronyms and abbreviations do include lowercase letters." http://en.wikipedia.org/wiki/Acronym_and_initialism#Represen...

L. O. L.