This passage is about meaningful prayer in order to form a spiritual bond with God. Often times people would use prayer as a means of receiving praise. They would purposely go out in public to draw attention to themselves so others would think highly of them. However, Jesus spoke against this, encouraging everyone to go somewhere private to pray and use prayer as a means of meditation and to strengthen ones relationship with God, not their social status. The original people hearing this understood it rather clearly as Jesus did intend this triad to be interpreted literally giving them thorough instructions on how to pray.
I personally feel that in today's society there is almost a stigma surrounding religion and so public