>SimAirport (why don't they get sued by EA?)

That is strange. The only thing I can think of is that EA isn't terribly motivated since they aren't trying to keep a broader "Sim" brand alive, just The Sims and SimCity (and it's not clear how invested they are in SimCity anymore).

Poking around U.S. trademark database, EA may not have a general "Sim" trademark— as Maxis' appears to have lapsed [0]—and maybe "SimAirport" is distinct enough from "The Sims" and "SimCity" trademarks EA has to not be worth suing over.

[0] https://tsdr.uspto.gov/#caseNumber=74300602&caseType=SERIAL_...