>>1114754In the case of city buses it makes sense, because they're not meant to go fast, usually no more than 50-60 km/h tops, which they'll likely rarely reach. Below 60 km/h streamlining will do little for fuel efficiency. However not being streamlined means that the driver can sit further in the front, leaving more space for passengers.
In the case of coaches idk, prolly what this guy said
>>1114758