I'd contend the name of the thing is now actually "Daylight Savings Time" instead of "Daylight Saving Time" as it was originally put into law.

Language is descriptive. If everyone calls a thing X, it is, by definition, called X.

"Everybody" disagrees with you:

https://www.google.com/search?sourceid=chrome&ie=UTF-8&#...

You're saying google's tendency to correct words spelling to ones it looks up in its entire database of text is conclusive evidence on modern usage of a word?

I'd say it's suggested search complete is probably more indicative about what "Everyone" is expecting when they type that term:

http://i.imgur.com/LqsSS.png <= Picture of what autocomplete shows you