CAPS: Cirrus Airframe Parachute System. Realistically it's not practical to retro-fit this technology, so you would almost invariably buy a plane with it.
Cirrus also solves the other problem that's of growing importance in the US with increasingly elderly private pilots - what if your plane is fine but the pilot is incapacitated (e.g. stroke)? Emergency autoland means the plane itself is capable of determining a suitable landing site, navigating there, broadcasting its intentions to other aircraft and landing, then switching itself off, meaning the passengers (and possibly the pilot depending on what exactly was wrong) survive the incident.
I don't know about "regularly" when they're citing one person who did most of these retrofits - that sounds like it's not happening very often at all, my uncle used to do GA maintenance in (the state of) Georgia, and never saw this as a Cessna mod.
But I'll concede that article makes it clear this is a real thing non-crazy people do which I was not aware of.
Cirrus also solves the other problem that's of growing importance in the US with increasingly elderly private pilots - what if your plane is fine but the pilot is incapacitated (e.g. stroke)? Emergency autoland means the plane itself is capable of determining a suitable landing site, navigating there, broadcasting its intentions to other aircraft and landing, then switching itself off, meaning the passengers (and possibly the pilot depending on what exactly was wrong) survive the incident.