It prints the same picture every time, but people's hands are almost always too dirty, so it never hurts to wash again. Oh, it does something. It makes you wait ten seconds while the anti bacterial soap works. It's really sticky stuff, so you have to work at it. Because there's a machine involved.
People respond to important - sounding machines, and special goop.
It's not easy to change behavior. It's not about what it cost to make the machine. This is a bargain. The jury on MLMS is still out. I'm Stan Patrick.