I'd like to see "% days vulnerable to publicly-known vulnerabilities" as a smartphone statistic

I wouldn't argue they were secure, just that nobody cared to exploit them because they didn't have any value exploited because it was just a phone. A modern smartphone has as much compute power as a computer from the 90's and a persistent internet connection. There is value in exploiting it just for that, let alone all the personal and financial data that they now house.

One of these days someone is going to be held to account in a civil suit for not fixing exploits and it's going to be very ugly for the manufacturers when that liability lands.