i think biometric payment cards are an easy to understand analogy
https://twitter.com/CarlstromJohan/status/1303303604816707587banks have normal payment cards already so they won't adopt biometric cards en masse until the technology has matured and the price is appealing to them, so companies who make the sensors are trying to innovate and drive the price down while still being able to make a profit
similar story with solar panels, we've heard the estimates for ages that solar panels will in theory pay for themselves after 10 or something years but they remain a niche market, people like musk want to make them attractive to shitloads of potential customers
