Why is Daylight Saving Time not called Daylight Savings Time?

In "Daylight Saving Time," "Daylight Saving" is being used as an adjective - as in time that is saving daylight. "Daylight Savings" would be a noun itself, and makes little sense applied as an adjective in this context.

Many people use the word savings, not knowing the correct way to say it.

Edit; "Daylight Saving" time.