From experience of CS1, most assets will be created for drive-on-right so still an issue. For transport vehicles the game should just be automatically setting the relevant side based on which side of road traffic drives on etc. So even if someone makes a drive-on-right bus and I use it on a drive-on-left city, the cims should get on/off via left side not right side (it will look weird due to doors on right side, but still less weird than cims walking through the bus to enter via right side of bus).