Article title is misleading, they only minimize some capital gains tax on their cash and investments with the nevada entity. And they certainly have a duty to shareholders to do so. They pay hundreds of millions in income tax on their profit in California, plus everything else - property tax, payroll tax, sales tax on purchases in CA...
A share in something could be a share in any social contract. A share in a nation, for example, accords one vote and a host of other rights and duties. A share in Whole Foods implies a share in some of the profits going towards nonprofit activities. A share in Google implies only a 1/10th control over their direction -- they come along for the ride.