Just a point on the distinction between motor_vehicle and motorcar - there are a number of countries and regions where the majority of road users are on motorcycle. So a road which is unsuited for a larger motor vehicle like a car, but is suitable for motorcycle travel, could be tagged like this.
However, in countries where this is the case this tagging is not common either because a) it’s assumed that for any road, most users are not in a car anyway or b) it is hard to verify if you don’t have a car anyway, are these lanes to narrow for cars? Regulations on this might not even be present so it could just end up being a guess