TfL contract bus services to said operators. TfL still have a duty of care to the staff Arriva, Stagecoach and the rest employ on TfL-contracted services.
I don't know what any of this has got to do with windows on London Underground.
If anyone thinks that a duty of care extends to ensuring windows are open (or masks are worn, or any other claims), then the onus is on them to create a thread in the appropriate forum section and present the evidence for these claims. Anyone making such claims can expect to be challenged, but this isn't the place for it.
Any such claims should be substantiated and discussed in the appropriate forum section.
