Using a basic smartphone is better, because the user does not store much data in it. In comparison though amazon is only allowing smartphone users to access their account, those who value their privacy will find that using a smartphone very risky.
The television channels are all discussing Pegasus software for stealing data, yet like the lawyer Prashant Bhushan mentioned, when a person installs any app, he is effectively give it permission to steal data from the smartphone.
Some people do not mind it, if their personal information is shared with others so use smartphones extensively, while others like the domain investor are paranoid about their personal information being shared, so they do not use a smartphone.