The bleed point is the next highest point. In case of a radiator cap which contacts coolant like this case the cap should be the highest point and the bleed nipple (if located) should be at a place where its known to trap air - (old Honda engines come to mind, if you filled them with coolant dead cold from empty the block would take an awful lot of time to fill and also warp in the process.
Now if we have a system which has the cap blocking the air pocket in the tank (mercedes benz/BMW/VW/Audi and some GM and chrysler vehicles) the tank is bled by a little pipe on the the highest point on the engines cooling system and fed tot he waterpump suction side. but the radiator or head would still sit lower than that - to remedy this the tank is placed at the back (higher point of the vehicle slopeline) as water will always stay level that ensures the engine and radiator will always be full under any condition.
Classic case - Mazda RX7 - the engine uses two caps that look like radiator caps - one is pressure type and one is just a lid. As the radiator is lying nearly horizontal on the cars bellypan for sure we know it will never fill the engine, so the cap was placed higher - and to further remedy the design as the bonnet was very very low on that car they installed another remote pressure reservoir - then finally a last expansion tank fit into the fender well.
Common case - Toyota Hilux with L series engine - the cap is placed on the engines coolant pipe flange - why - height..
