Economies or scale... How about just power? These companies have too many people in their pocket. When you have enough power you can get away with this. These companies, even if not paying taxes directly, are huge contributors of economy. You threaten them, and they threaten you back. Do you want them to take their 10,000 jobs somewhere else? It's not tax laws and enforcing them, just rather just too much power on too few people's hands.