Rail can support freight of course and complements trucks very well. Rapid transit can’t really support freight if it wants to operate at any reasonable frequen

Rail can support freight of course and complements trucks very well. Rapid transit can’t really support freight if it wants to operate at any reasonable frequency - you just can’t load any real quantity of freight in a few minutes. Even baggage is stretching it a lot of the time on busy lines. And the slow acceleration times and length of freight trains severely conflicts with the needs of passenger rail. Therefore, freight and passenger rail need to be separated for either to perform well. On the other hand, cars and trucks are a lot more similar in performance and size, so they can share the same roads just fine - it’s only an issue if the road is completely choked with trucks.