Why is there no mention of the people in London in the poem 'Composed upon Westminster Bridge' by William Wordsworth?

Wordsworth does not speak of the peopled bustling city because his subject is the comparison of the city’s calm in the early morning (before people are out of bed) to the calm of nature: "Earth has not anything to show more fair...." He is struck by the way the city’s structures (“domes, theatres, and temples”) are like Nature’s own creations--“valley, rock, or hill”--and how the calm river Thames seems to have a will of its own. In this fourteen-line personification of the city (“that mighty heart”), Wordsworth is tying humanity’s existence to Nature, a primary Romantic observation.

In other poems Wordsworth does treat the city population in considerable detail (see The Prelude and "London, 1802"); for example, in The Prelude, "Residence in London" (639-649), the blind beggar on the street seems to admonish him as if "from another world”: "I gazed, / As if admonished from another world." Note: In analyzing poetry it is always dangerous to inquire into what is not dealt with. Remember Eliot's admonishment: "A poem must not mean, but be."