But a lifetime of 3y doesn't jive with why my 7 year old vehicle is mostly fully functional. Even with 10% over-provisioning (amazingly expensive 7y ago), that's only a 15% reduction in 7 years.
The statement "The life of the commonly used chemistries is only around 3 years" is completely misleading and probably inaccurate.
I don't know about the 3 years number, but generally speaking battery lives are estimates/averages based on statistics. If you have a battery that was well cared for it will outperform the average. Also sometimes it's just dumb luck. One aberration isn't nearly enough data to throw out the entire premise
Phone batteries are lithium polymer pouch cells, the least durable type commonly used. Car cells with lithium ion NMC cylindrical cells are much better, and LIFEPO4 in turn is several times more durable than that.
You would be wise to insist on an EV with LIFEPO4 batteries in the sense that calendar lifetimes are more likely to be on par with traditional engines.