But since a quarter of large corporations - $50m in sales or $250m in assets - don't pay any income taxes at all due to loopholes and offshore sheltering schemes...
Kudos on citing your source, but you're completely misrepresenting what the article says. The article states that, overall, two thirds of corporations don't pay income taxes, meaning that large corporations are actually better at paying taxes than other corporations. Furthermore, the article states that the "vast majority of the large corporations that did not pay taxes had net losses... and thus no income on which to pay taxes". Claiming that large corporations don't pay taxes because of loopholes and sheltering schemes is patently false.
Machines have less problems. I'd like to be a machine. -- Andy Warhol