Why does Lego state early purchase of new sets for VIP memebers only and when you go to Toys r Us they are on the selves?

That's not the new sets they're talking about. This month is was the new Ferrari set (10248). It was available to VIPs only starting on July 15th. If you went into a LEGO brand store and tried to purchase it, they wouldn't let you buy it without a VIP membership. They do this as a way of getting you into the VIP program.

It's usually the most notable sets that went on sale two weeks early such as the Tie Figher, Tumbler, Helicarrier, modulars (Parisian Restaurant, Detective Office, etc), "expert" creator sets (Ferris Wheel, Mixer, Mini Cooper).

I'm not sure how long they've been doing it but it's only for most anticipated sets (and AFOL targeted). Technic, regular City and other non-licensed themes like Ninjago and Chima don't normally make the grade though the new Ninjago set is the August early release I think. That set is breaking new ground with Ninjago!