Every time I take a city bus, a very simple question pops into my head: why do city buses not have seat belts?

My intuition is straightforward. City buses have short distances between stops, usually run at lower speeds, and involve frequent boarding and alighting. If everyone had to buckle up, then buckle off at every stop, that whole sequence would slow operations down a lot. More practically, city buses are designed with standing areas. If seated passengers must wear seat belts, what about standing passengers? To fully resolve that contradiction, we would have to remove standing areas, and that would fundamentally change the bus's capacity model.

During this year's Spring Festival period, I happened to take a longer-distance bus route in my hometown, running from the city center to suburban areas. The vehicle looked like a standard coach bus. Every seat had a belt, and passengers were clearly required to sit one person per seat, with no standing allowed. At that moment, the issue became much clearer to me: the key is not a standalone technology choice, but the operating scenario.

Later, I looked up more information, and this judgment broadly holds. The Dutch road safety research institute SWOV, when explaining why seat belts are not mandatory on public transport, highlights two practical reasons. First, frequent stops and high passenger turnover make mandatory seat-belt use hard to enforce. Second, once seat belts are mandatory, standing passengers are effectively incompatible, while standing areas are central to city bus capacity design. That almost directly confirms my original intuition: seat belts would reshape the entire operating logic.

Regulations reflect the same classification logic. China's Motor Vehicle Running Safety Technical Conditions (GB 7258) distinguishes vehicle types by usage and passenger organization. For highway coaches, tourist coaches, or public buses without standing areas, seat belts are generally required for seats. For urban buses that allow standing passengers, different requirements apply. In other words, the standard itself recognizes that a standing-allowed city bus and a fully seated coach are fundamentally different types of transport.

The same pattern appears in long-distance operations. China's Safety Technical Conditions for Commercial Buses (JT/T 1094-2016) requires all seats on commercial buses to be equipped with compliant seat belts. These vehicles usually run on highways or longer routes, do not allow standing, and assign one seat per passenger. Under those conditions, the risk focus shifts from "falling during sudden braking" to "being thrown from the seat in collisions or rollovers." U.S. transportation authorities have emphasized similar logic in seat-belt promotion for over-the-road buses: severe outcomes in high-speed crashes make seat belts especially valuable in reducing casualties.

When I put these two scenarios side by side, the difference becomes clear. City buses prioritize high turnover and convenient boarding, with built-in standing capacity and low-to-medium speeds over short trips. Their risk profile is more about sudden braking, crowding, and falls. Long-distance or high-speed passenger transport, by contrast, is built around keeping each passenger fixed in a seat to reduce secondary injury risk in serious crashes. No standing is allowed, seating is fixed, speeds are higher, and routes are longer, so the value of seat belts becomes much more direct.

So I now see this less as a simple "useful or useless" question, and more as a system-level tradeoff. Safety equipment is never isolated. It is always embedded in a concrete usage context. City buses and long-distance coaches may both be called "buses," but in practice they solve two very different problems.