Last week's letter from MZ: Is it harder to find a long-term romantic partner in big cities or smaller towns? Mike Munger says transaction costs are part of the answer because they create some stickiness like brand loyalty. In politics, for example, buying votes can increase trust and make system work better by preventing corrupt bargains. But if you have many different small patents that don't apply to each other, then less effective software will be written due to reduced transactions cost.