1. Incidence is tricky--the costs of taxes or regulations (or benefits of subsidies) can be shifted. Below is the abstract of a paper by UNC economist David Blau; he finds that the cost of a child care center regulation is borne by the employees of child care centers.

The effects of regulations governing staff-child ratio, group size, and staff qualifications in child care centers are estimated, using data on a sample of centers. The data contain measures of staff characteristics and wages, price of the service, and the developmental quality of the child care provided. Regulations vary across states, but may be endogenous to these outcomes. Estimates with state fixed effects are feasible because regulations vary within states by age group of children and job title of staff. Estimates with state fixed effects show that tougher regulations have some impact on input use, but have little or no impact on price and quality. The most striking finding is that tougher regulations reduce staff wages, suggesting that the incidence of child care regulations is on employees of day care centers.

2. Another entry in the incentives matter category--below is the abstract of a paper finding that higher welfare benefits increase the incidence of single mother families.

This paper uses data from the eight waves of the European Community Household Panel (1994-2001) to estimate the impact of welfare benefits on the incidence of single motherhood and headship among young women across European countries. The regressions include country fixed effects as well as time trends that are allowed to vary by country, to account for fixed and trending unmeasured factors that could influence both benefit levels and family formation. The analysis also accounts for individual characteristics and labor market conditions. The results suggest that benefit levels have a small but significant positive effect on the prevalence of single mothers. An increase in yearly benefits of 1,000 euros is estimated to increase the incidence of single mother families by about 2 percent.