What does it mean to "offer the same terms?" Presumably the unionized folks are getting some compensation benefit compared to non-unionized (otherwise, what's the point?)

Since the terms are already different, how do you compare if the union rate (no CC tips) is better than the non-union rate (with CC tips?)

The raises and tips that Starbucks was giving to the non-union stores, but not offering as options to the unionized stores.

What do you mean by "options". Was there an active negotiating going on at this time (maybe?)

Starbucks did not offer to negotiate these new benefits with the unionized stores. They rolled them out to non-union stores, then made a lot of noise about how they couldn't possibly give them to the union stores, because the union was preventing it—but they didn't actually engage in any negotiations with the union, offer the benefits, or in any other way show good faith.

It is painfully clear that this is a deliberate union-busting tactic on Starbucks' part. The only reason they gave any stores these benefits is in order to make the union look bad.

This is illegal.

I don't know labor law, but if you're right, it's completely ridiculous. I know for a fact that union employees are allowed to receive benefits and pay increases that non-union employees don't get. If the other side of the coin is illegal, then the law is insane.

Specifically because it's a union-busting tactic, employers cannot give benefits to non-union employees that are not at least offered to union employees.

Remember, the employer/employee relationship is an inherently unequal one. The freedom of the employer to do certain things is curtailed for the common good, in exchange for substantial power and economic advantages.