UA flight from FRA was cancelled yesterday due to mechanical issues. I got an email from “customer appreciation” with a link to receive compensation in which they gave a $100 ETC. I immediately contacted them requesting EU 261 compensation and today got offered 600 EUR, 50K miles, or $1000 ETC.
I think the initial email is intended to be deceiving, so most costumers will just be happy that United proactively offered compensation, not knowing they’re legally entitled to much more.