United Parcel Service Inc. jacked up fees by 30 percent to $650 for the largest items it delivers to discourage shippers from putting kayaks, refrigerators and other oversize items into a network meant for smaller parcels.

Joyce Brenny, chief executive of Brenny Transportation in Minnesota, gave her truck drivers a 15 percent raise this year, but she still can't find enough workers for a job that now pays $80,000 a year.

Using traditional product packaging in e-commerce can hurt the bottom line. For many companies, the practice triggers unnecessary, counterproductive costs several percent of their total cost of goods sold (COGS).

President Trump has personally pushed U.S. Postmaster General Megan Brennan to double the rate the Postal Service charges Amazon.com and other firms to ship packages, according to three people familiar with their conversations, a dramatic move that probably would cost these companies billions of dollars.

Established U.S. logistics firms say digital-friendly freight startups that are drawing growing interest in Silicon Valley still lack the scale and customer relationships to threaten their share of the market.