Why do American launch rockets use tracked platforms during transshipment?

Because you are talking about two different situations. The launch of the launch vehicle needs to transport all the components of the launch vehicle to the launch site for assembly, and then transport them to the launch pad to be erected for launch. According to the different methods of different countries, the three-level method of the Soviet Union and the three-level method of the United States are typical. Even the same method, the specific operation will be different. When you say reptile, you actually mean the transshipment of Saturn V and the American space shuttle. Because both of them are huge in volume and mass, after being assembled and tested in the world's largest vertical assembly workshop, the platform and the carrier rocket on it are slowly transferred to the launch site for unloading by the rambler crawler transporter. And the track you see actually refers to the assembly workshop. Many times the launch vehicle is not that big, such as our Long March series, such as the American Cosmos series and so on. Therefore, Saturn V does not need vertical assembly workshops and rambler transport vehicles, not to mention the huge and expensive supporting equipment that is only available at Cape Canaveral and not available at the Vandenberg launch site. Therefore, some vertical assembly before launch is simply completed in a relatively simple service tower, and it is mainly vertical hoisting anyway. The whole tower has a track, which can be slowly towed and moved to the launch pad, and then the launch vehicle is unloaded and launched.