> "The top credit-card merchant fee actually rose in the United States between 1991 and 2009, and this is a goddamn tragedy, since these fees are baked into the cost of most retail goods and thus born by the working poor (who pay them even if they use cash.) . . . Why are these IT-focused industries so consistently immune to the same technological improvements and cost reductions we see everywhere else?"
The simplest apparent answer is that this (the provision of payment services) is not a competitive market and as small retailers have nowhere else to turn, they're forced to pay high rents to what would have been called a trust in late 19th century Gilded Age terminology.
The solution is also fairly clear: if you have what's called a 'natural monopoly' then it should be state-owned and state-managed (see the network of roads, water pipes, etc.), and if it's not actually a natural monopoly - meaning a system where competition doesn't make sense, i.e. having multiple networks of privately owned roads is silly - then you need anti-trust actions by the government to foster competition in the industry, which would reduce fees and costs for merchants.
Arguably, if consumers had to pay the cost of transactions, rather than merchants, you might seem a lot more political pressure to make credit/debit card transactions the same cost as cash transaction, i.e. no added cost.
Cash is a government-supplied taxpayer-supported service supplied free of charge for merchants and customers, so perhaps that's the best option for the credit/debit interface as well. Of course, this would allow government to track everyone's individual non-cash purchases, but then they already have access to the credit/debit ledgers, don't they?