What several other of our experts are going around, Verlangen [Herzlich thut mich verlangen?] is the concept that an expression which has a plural construction can actually be a singular. 'Wages" in this context is such a construction and is perfectly good grammar, since the singular subject (even though it has a plural form) goes with the singular verb.

Here's another instance:
"When you awaken, what you first see on the beside table is a glass of water, a napkin and a spoon." You might think that the enumeration of 3 items is inconsistent with the singular 'is', but no. In this instance, the items enumerated constitute a collection, or a scene, which is the subject of the verb and is treated as singular.