Originally Posted by lrdpenn

My guess...nothing to do with cost, simply bare minimum competitive matching.

Delta doesn't offer free wifi on international, and it makes an easier cutoff point to exclude integrating logins / cutting deals with the Samsung wifi.
United will offer free wifi with starlink but practically they have a long way to go, and they are starting with regional first.

I agree with others here that Delta and United have made a splash with their "free" wifi but it's been (or will be) a mess in reality whether a particular aircraft has free wifi or not.