I'm sorry if I came across as insulting; it wasn't intended. The thing you seem to be missing is the size of the base on which the tax is imposed. As I pointed out earlier, 30% of $50 is still less than 20% of $100.
Didn't take it as insulting at all. Look at the history of the bases relating to the corporate tax schedule. In the 1960s the base for a 52% rate was $25k. Reagan's tax cuts in '86 resulted in that rate dropping to 16% over $25k. Today it's 15% under $50k. The rates today are all lower than they were under the Reagan tax cut plan, and throw in the exemptions and credits and it helps explain why so many of the largest companies pay no taxes or even negative taxes.
The Pfizer story is rather interesting and from your links there appears to encompass more reasons than simply their 12.5% tax rate. According to one article, their effective tax rate here was around 7%. Labor may be a big factor because the article says they are charging 12 times the price for pharms they send here that what they are charging over there. Ireland dropped those corporate taxes to entice companies to come in and hire. It worked for Ireland for a while but then they went into a far worse recession than we did here. They're still trying to recover, but they still have to collect taxes from someone, just as we do. The one thing we're likely not to know is the whole story of why Pfizer is over there.
For most companies here, the actual tax dollars paid as a major decision factor pales in comparison to the complexity of the code itself, regulatory burden that hinders growth and even operation, and the high wages demanded here in some jurisdictions compared with other countries. At a time when the US economy has shifted from manufacturing into credit and financial markets, and the wealth gap continues to increase, Republicans may have a tough sell on significant reductions in tax revenues from one sector without a clear showing of how that will be either made up in another sector as deficits and debt continue to be the elephant in the room.
