Building is running ahead of the country here: 21.0 units permitted per thousand households against 11.0. Across 1,892,613 households that means roll-off demand from builders alongside the residential hauling.
14.1% of Phoenix residents moved in the last year, against 12.3% nationally. Moving is what generates junk: the garage that never got cleared, the furniture that does not fit the new place, the tenant who left half a flat behind. Across 1,892,613 households, that churn is the base load.
Phoenix has 1,892,613 households across a population of 5,028,754. Junk removal demand tracks households more closely than anything else: people move, renovate, downsize and clear out, and every one of those is a job for someone with a truck and a crew.
Where these figures come from
Every number in these paragraphs is a Census figure for the Phoenix metro, compared with the national figure from the same table.