I’ll contend the old MPE operating system, while non-open source since 1972, was trusted by its users to “not” do something untoward with user data.
Too bad the MPE O/S, dies by its own clock at the end of 2027 and the number of sites still using it is about less than 10K, maybe even 1K. There is a 3rd party patch that will extend it for 10 more years. The only other means is to “lie” to the O/S. (Enter an earlier date at boot up.)