I'm having a hard time sorting out their methodology, but it looks as if the problem is that there just weren't any "anti-" groups opposing the measure, at least by their calculation. They totted up only $1.4 million spent by all the "anti-" groups, which is practically nothing compared to the billions spent on all of the Senate campaigns put together.
Neither, in fact, is that $55M spent by "pro-" groups all that large. This is the problem with the "campaign fund bribery" theory. These groups are heavily constrained in how much money they can give, just $10,000 to each candidate. These candidates need millions.
Their contributions just aren't big enough to make a bribe. It's not even enough to get them to take a meeting with you. Rather, it's the other way around: they contribute to the candidates that they want to see win the election.
EVERYBODY on this list got more money from the "pro-" groups than from the "anti-" groups. Kelly Ayotte voted no; she got $326,335, compared to $31,751. Mike Crapo, $181,414 vs $15,020. Ted Cruz, $529,897 vs $19,050.
What this data indicates, if anything, is that there just weren't many groups who opposed this. The direct marketers, the catalog sales, and computer manufacturers. That's it. Weren't there any consumer groups? Consumers are the ones who pay the tax. None of the consumer groups took a stand? Or did their crappy methodology just miss them?