Why does ZTO small items use large items express delivery?

To send large goods, express delivery is too expensive, logistics is too slow, and there is no pick-up and delivery. On August 1, 2016, Zhongtong Express headquarters newly established Zhongtong Express Company, which specializes in undertaking large goods. The same speed and timeliness as express delivery, and free door-to-door pick-up and delivery. The price is cheaper than express delivery. Electrical appliances, heavy goods, bulky goods, wine, micro-business bulk goods, etc. can all be sent to ZTO Express. ZTO Express is not ZTO Express. For express delivery, small items go to ZTO Express, and large items go to ZTO Express.