One reading in the textbook, on mega-cities, said that the people of Mexico City ‘live their lives in the street’. One student, obviously thinking about the homeless people around Sydney’s CBD, asked what that meant. The reading goes on to mention taco stands, people meeting and socialising, Mariachi bands and people of all ages dancing in the street. My usual question is ‘Is this a good things or a bad thing?’.
There may be distinctions between living life ‘in the street’, ‘in the streets’, ‘on the street’ and ‘on the streets’. Google Ngrams shows that those four are about equally used. It would be necessary to consult an appropriate corpus to find out which ones are more used to mean ‘party atmosphere’ and which ‘homelessness’ (among other meanings).