These sorts of programs seem to apply to “shortsighted” spending though not so much to “selfish” spending.

First, we need to reframe the question. Do the poor express a desire to build assets and do at least some of them express frustration with their ability to build assets because of temptations of various kinds (incl. temptation goods)?

The answer to that is unequivocally, “Yes” based on lots of high quality research including but not limited to Duflo and Banerjee’s paper and Portfolios of the Poor.

Then the next question is, “Are there low cost interventions that have proven efficacy at helping those who want to build assets and avoid temptation do so?”

Again here the answer is unequivocally, “Yes.” See for instance Karlan on commitment savings, Karlan on Commitment contracts to quit smoking, Dupas on Savings accounts, Duflo and Banerjee on timing of fertilizer sales and Linden on timing of conditional cash transfers based on school attendance.

In each of these cases the costs are minimal and the evidence is strong that these interventions help the poor invest in building assets be that financial, physical or human capital.

Now there is a final question of relative efficacy of these interventions versus others. I have a bias towards these types of interventions because they are at least neutral and often positive in terms of reinforcing the agency of the poor.