Multiple user accounts with secondary passwords

a family/group, etc. with 3 computers or more on the same account should be able to have an adim/master password and yet each user/individual computer should have it's own password to protect it from prying eyes within the network/family, one sibling not being able to spy on the other and yet each with the ability to secure there own settings/logins, etc and the parent/admin being able to oversee all and yet retain privacy of the superior master password for the overall account. I had assumed that would be the standard arrangement but was very disappointed to discover it was not…To me it's a "no brainer"