My dad worked in a datacenter and in secured areas he had to badge in and put his hand on a scanner that took a photo of the back of his hand. It was quite secure and occasionally would refuse him entry if he had a bruise or recently trimmed his nails. It was good enough for a company that makes the world’s most used desktop operating system and was sued by the EU for bundling the browser.
This was back in 2002 btw. I can only assume it’s gotten much better and now includes things like surface vein mapping (doable with the IR sensitivity of a lot of COTS cameras)
