Redundancy is our friend. All languages are filled with redundancies of one sort or another. ATM machine is one example. The value of that redundancy is that there are other things in the ATM universe, such as ATM card, and specifying that you are talking about the machine itself can be an important thing. Also, saying ATM machine makes it clear that you do not mean the expansion of ATM to be Asynchronous Transfer Mode, a point that may or may not be entirely clear from context. Another common redundancy of this sort is the phrase AC current. In this case it is important to distinguish it from AC voltage. This latter phrase could be disparaged as being a contradiction in terms, but to do so would be as inane as disparaging AC current as redundant.

Other types of redundancy that are common in various languages include subject/verb agreement, use of a plural form of a noun when a plural determiner is attached to the noun, and agreement in number, gender, and case in adjectives with their corresponding nouns. Failure to use these redundancies is a mark of ungrammatical usage.