One of them is an MBTA customer outreach effort that's a few years old --- their "Customer Bill of Rights". They want you to know that you have the right to prompt service. To safe service. To a refund in case of excessive delay.
The other is a poster for the "Transit Watch" program, in which they were searching the bags of Orange Line passengers during the Democratic Convention a year or so back. They've since announced they'll discontinue the searches, but they didn't take the posters down; the signs are still up, telling people that if they don't allow T employees to paw through their baggage, they may be asked to leave. The right of the people to be secure in their persons, papers, and effects is not part of the Customer Bill of Rights.