Trailer Coverage under the BAP

I have a question about the business auto policy. The policy declares that it covers trailers with a load capacity of 2,000 pounds or less designed primarily for travel on public roads. But, the definition of “trailer” includes semi trailers which are clearly going to be over 2,000 pounds. And, since the definition of “auto” includes a trailer, it seems that any liability coverage that applies to autos is also going to apply automatically to trailers, regardless of size. Can you clarify this situation?

Maryland Subscriber