Originally Posted by Squirrel27

Especially because the technology exists and has existed for a long time. EICAS isn't ground breaking stuff here. The A320 was certified with an ECAM in 1988! There are plenty of examples of 737 pilots disagreeing on what checklist to run, and then ending up running the wrong one. Doesnt happen on an EICAS equipped aircraft.

Why hasnt Boeing integrated it into old fleets?

Money. Full stop.