If two SUV owners live in the same city but one has basement parking and a 20-minute commute while the other parks outdoors and drives two hours daily, why should city alone never determine the recommendation?

Because the two recommendations come out opposite, and a variable that produces opposite outputs from the same input was never the variable doing the work. Here are both answers in full, in one city, from one range. Owner A parks in a basement at home and a basement at the office. The cabin is never heat-soaked, never stands in the sun, and is almost in laboratory conditions from one morning to the next. He is inside it for roughly twenty minutes each way, usually alone, windows up, climate control doing very little because the city's climate is mild enough that the air conditioning runs for comfort rather than rescue. Nothing wet gets loaded. His exposure is short, stable and private. The right answer for him is a strong spray used at the door, at a dose he would never get away with over hours, sited wherever is convenient because a gradient between rows does not have time to matter in a vehicle he sits in alone. He should judge it immediately, because the whole journey is the first impression. He needs no hardware whatsoever, and a dense scent he happens to love is perfectly safe at twenty minutes. Owner B leaves the same model of vehicle on an unshaded bay all day and spends two hours in it, sealed, often with colleagues who are in there every day and will never say anything about the fragrance. Every line of his answer inverts. A mild continuous hanging rather than a spray. A low dose, set for the end of the two hours rather than the start, because the cabin accumulates when it is not exchanging air. Placement deliberately behind the front row, so the driver is not sitting in the strongest part of a gradient that now has time to build. A judgement taken late in the journey and not at the door of a vehicle lifted off a warm bay — and taken from a passenger getting in fresh rather than from him, because by hour two he is the least reliable nose aboard. And he has the only genuine hardware case of the two, because his vehicle has two states in one day. Five lines, five inversions, same city, same shop. Now the concession, because it matters. The city shorthand describes Owner B quite accurately — a Bengaluru commute whose distance would be twenty minutes anywhere else really does occupy far longer than the route suggests, and most owners here are in Owner B's position rather than Owner A's. That is why the shorthand survives and why it is worth publishing. It is still a shorthand rather than a rule, and Owner A's conditions look far more like the short-occupied-time pattern of a dry inland city than like his own: his conditions win and the city loses. Three lines that hold for both of them. A fragrance adds a scent to a cabin and removes nothing from it — if either vehicle has something in it, Fragrance will not remove this and that comes first. And nothing here is a claim about driving, alertness or safety.