Convenience is consumers' paramount value, at least as it has appeared in recent installments of "The Payoff". Seattle-area startup Qthru offers a new variant on the in-store shopping experience, with a priority on convenience.

This week several news items speak to relatively modest ambitions of companies working in payment systems: rather than perfection over a wide domain, they seem to aim at incremental gains.

One of Amazon's advantages over physical retailers has been that its sales have largely been free of state sales tax. That just changed.