To what extent this pattern reﬂects a “home bias” in banks’ investment portfolios is hard to assess, given that investment patterns depend on preferences, incentives, regulations, and transaction costs. The regulatory treatment of sovereign debt certainly affects portfolio choices of banks (Deut​sche Bun​des​bank 2014, 2017; Kirschenmann, Korte and Steffen 2017).
If we want to save oil, for example, it is useless to appeal to the conscience of citizens, it is enough to increase the price of petrol and diesel; if we want to protect the environment from petty pollution by the public we can only educate citizens to be conscientious.