The Transportation Intermediaries Association has published a document to its members citing IRS publications that note the following:

Payments to companies for the transportation of freight are exempt from 1099 reporting

From https://www.irs.gov/pub/irs-wd/9932048.pdf:

Section 1.6041-3(d) of the Income Tax Regulations excepts freight payments from
information reporting. Section 6041A was added to the law by § 312(a) of the Tax
Equity and Fiscal Responsibility Act of 1982, 1982-2 C.B. 561.

Read more directly from the IRS below
• 1999 IRS Chief Counsel Memorandum
• 2014 IRS Chief Counsel Memorandum