I bought a house with these and didn't realize it had this feature for like a year (batteries had died). Now I love it. I find myself taping every faucet it use and am annoyed when others don't turn on.
I actually bought a handfree soap dispenser to go next to it, which is a great combo. Preparing meat or something, I can clean my hands and tap sink with elbow and not worry about cross contamination of everything.
More likely the ones left are on some work visa and do not have as much freedom to leave.