This suggests that while we may indeed be plucking the innovation low-hanging fruits, it might not be because we lack a supply of innovation, but because we're exhausting the easy demand for innovation.

This makes a lot of sense. On the podcast Startups for the Rest of Us, they say that solutions to problems are either aspirin or vitamins. Entertaining movies are a vitamin, because they're fun to have, but people didn't feel like they had a lack of entertainment problem before cinema was invented. Flush toilets are an aspirin sort of solution, because bad sanitation is a really obvious, really unpleasant problem. Though, most of the "aspirin" examples they use are more like email than flush toilets, so maybe flush toilets are more of an antibiotics innovation than an aspirin innovation. By that standard, there aren't many antibiotics-level innovations left outside of medicine, for the parts of the world with the most money to fund them. (I could also see there being some left in ways of avoiding or dealing with pollution, and psychological and social things.)

Tyler Cowen made the interesting point that the internet isn't as innovative as the flushing toilet (or indeed the television). He certainly has a point here: imagine society without toilets or youtube, which would be most tolerable (or most survivable)?

I'm probably missing the main point of the article here, but this is really interesting to think about.

Are we assuming that everyone keeps using outhouses if there are no flush toilets? Just from thinking about it for a few minutes, I can picture a relatively sanitary city where people defecate in plastic bags and trash pickup is much, much more frequent to account for that. If we were still using outhouses, communication technology (including the internet, but before that, telephones etc.) would be really important as a way of letting the population spread out (and work from home) to avoid sanitation problems.