What are the perks of being a tenured professor at U.S. universities, besides having academic freedom? For instance, one of my professors went to Princeton (for his undergrad math degree) for free, because his parents are tenured faculty at Princeton.  Is such a benefit available to tenured faculty at most U.S. universities?  This is assuming that a tenured professor's children are qualified to be admitted to the school.

Besides having academic freedom, what are some other, lesser-known, considerable perks of being in academia as a tenured professor as opposed to being tenure track?

(Main motivation for the question is to follow up on a previous question in which the OP asked about the stresses of academic life, specifically, in mathematics research.)
Universities offer all sort of "benefits" to its employees. Some of these "benefits" do  not have a monetary value (e.g., flexible work schedule). The benefits available to faculty are often different from the cleaning staff. Further there are differences in benefits between tenured/tenure track and adjunct faculty. I can only think of three benefits, that have a monetary value, for which there are differences between tenure track and tenured faculty

Sabbatical: Some universities do not permit pretenure sabbaticals. It is often hard to differentiate if sabbatical eligibility is tied to tenure or time in service. Brown University provides different sabbatical benefits pre and post tenure.

Housing Assistance: Some universities provide housing assistance (discounted homes, mortgage assistance, loans, etc). Portions of the housing assistance program at Columbia requires tenure.

Parking: Some universities provide parking passes. Carroll College provides reserved spaces for tenured faculty while other faculty and staff simply get a parking pass.

In terms of perks that do not have a monetary value, this varies widely by department. Tenured faculty often get to be chair of the department (which may or may not be a perk). Departments may also give tenured faculty priority in terms of teaching schedule, departmental and university service requirements, office space, and lab space. The sabbatical system, internal funding, and administrative support may be skewed in their favor also.