Question

Read the following passage and answer the question that follows. Passage: "The rise of the modern city has been accompanied by a pollutant that is rarely regulated as one: noise. Unlike smoke or effluent, unwanted sound leaves no residue to measure, and its costs surface obliquely — in hospital admissions, in school report cards, in the error logs of night-shift workers. Children schooled beneath flight paths show consistent deficits in reading comprehension and long-term memory, deficits that survive controls for income and air quality. The mechanism is not mysterious: the brain treats unpredictable sound as a standing threat, diverting working memory toward monitoring and away from the task at hand. What makes the problem politically stubborn is that its victims seldom connect their fatigue, or their children's restless sleep, to the decibel ledger of the street outside. Noise abatement, moreover, is a public good with diffuse beneficiaries and concentrated costs — the airport, the highway authority, the late-night freight operator — so every proposal to quiet the city collides with an organised lobby. Some economists propose treating acoustic space the way cap-and-trade schemes treat emissions: a fixed budget of permitted noise, auctioned to the noisiest bidders. The idea is elegant, but it stumbles on a moral objection — that silence, unlike carbon, cannot be averaged across a population, because a decibel that ruins one person's sleep cannot be offset by quiet somewhere else." According to the passage, why has the regulation of noise lagged behind the regulation of chemical pollutants?