Comment by sgammon

"Your data" is not actually being sent off your device, actually, it is being scrambled into completely unusable form for anyone except you.

This is a much greater level of security than what you would expect from a bank, for example, who needs to fully decrypt the data you send it. When using your banking apps over HTTPS (TLS), you are trusting the CA infrastructure, you are trusting all sorts of things. You have fewer points of failure when a key for homomorphic encryption resides only on your device.

"Opting-in by default" is therefore not unsafe.