Endogenous Price of Lighting Services

Another potential issue with the Tsao and Waide and Tsao et al. work on demand for lighting is that the price of lighting services is to some degree endogenous. If this is the case then estimates of a model of the sort suggested in my previous post will be subject to simultaneity bias. So why might the price be endogenous?First, there are the usual reasons that we are not separating the effects