Amazon One palmprint biometric opacity

TechCrunch has discovered that Amazon is offering customers USD 10 for their palmprints when they sign up for its contactless ID and transaction service Amazon One. 

Customers can use One in a number of Amazon checkout-free stores to pay for goods by holding their palm over a scanner. 

Despite promising to secure biometric data using encryption, data isolation and secure zones, TechCrunch reports that some palm data is used anonymously to improve the system, raising concerns about unstated potential commercial and other uses.