Agree, it's quite common in English to say 'the newspaper' rather than 'a newspaper'. I think newspaper is a special case. If you were asked 'Where did you read that?' it would be more natural to respond 'In the newspaper' than 'In a newspaper'. Conversely you would normally reply 'In a book' and only use 'In the book' if there was already a specific book established in the context.
Your English is wrong. It's not "They reads newspapers". Its "They read newspapers". Reads can only be used on a singularity