what information do such newspapers contain?
Issues regarding homelessness and poverty, information on policy changes and  advocate for the homeless and poor.
Street newspaper
Most street newspapers report on issues regarding homelessness and poverty, sometimes functioning as a main source of information on policy changes and other practical issues that are relevant to the homeless but may go unreported in mainstream media.
in which countries are street newspapers popular? Germany and Sweden.
wiki:24499235
Street newspaper [SEP] Coverage
Most street newspapers report on issues regarding homelessness and poverty, sometimes functioning as a main source of information on policy changes and other practical issues that are relevant to the homeless but may go unreported in mainstream media. Many feature contributions from the homeless and the poor in addition to articles by activists and community organizers, including profiles of individual street newspaper vendors. For example, the first edition of Washington, D.C.'s "Street Sense" included a description of a prominent homeless community, an interview with a congresswoman, an editorial about the costs and benefits of taking a job, several poems about homelessness, a how-to column, and a section for recipes.