"Malthusian" is not the simplest explanation. What about Marshallian? It looks like most of these behaviors involve doing something until marginal costs reach marginal benefits. His model involves doing things because they can't be as good as possible without having negative side effects. While this gets you the right result in some cases, it means he needs a separate model for explaining positive externalities ("Why do my neighbors clean their lawns, even though they get a fraction of the total benefit of living in a neighborhood with clean lawns?")