It is not necessary that the consumer be able to identify the specific manufacturer. Rather, the mark need merely to communicate to consumers that the goods or services bearing the mark come from a unique source, distinguishable from all the other sources for those goods or services. The government grants trademark owners the right to exclude all other businesses from using a similar mark on related goods or services. Because the government can enforce this exclusivity, trademarks are considered assets of a business, and thus can be licensed or even mortgaged as collateral. They allow businesses to build an identity and reputation with customers, and thereby grow or expand.
Trademarks also allow individuals to be better consumers.
In fact, Trademark law is the original consumer protection statute. It ensures that consumers can repeat their positive buying experiences by searching out familiar brand names, and avoid bad buying experiences by steering clear of brands they didn't like. It appears to be common usage to refer to service marks as either trademarks or service marks. Some trade names are also used in a way that makes them trademarks as well. If they use the former, then ACME remains a trade name only.