There must be some areas, maybe 50-100 miles apart, that need fast, constant freight transport? A smaller tube to handle mail, small packages? Get some experience with freight - no humans involved, no 0.5g limits. You have to crawl before you can walk. Space flight was payload, monkeys, and dogs before humans.
Just as Musk concedes that his concept is useless for trans-continental service (because supersonic flights are greatly more efficient, and allow flexibility to ANY city), freight may not work that well with the tube concept.
The biggest issues I would see are the loads and sizes, and what your current competition would charge. The tube capsule must be a certain size/shape, which would limit some palletized shipments. So then as a tube capsule transporter, you're going after a somewhat smaller market by weight and size, even after you're already at a price disadvantage compared to traditional trucking (and that doesn't even get into the comparison with railroad's even greater cost advantages).
Truckers are paid, what, maybe $.60+/mile as owner/operators, to transport items? Then tack on maybe $.20/mile for the company's profit. Round up to a simple $1/mile for simplicity of calculations.
Using St. Louis to Chicago (since I'm familiar with that distance
), it's about 300 miles. So for $300, you could haul a truckload of stuff (assuming no super heavy weights), in well under 1 day's time. Compare that with EM's estimate of, what, maybe $80 per person for a transit ticket from LA to San Francisco?
And on top of it - you STILL have to pay a local trucking company to handle the freight at the tube station, and make your local delivery. Not to mention that many freight loads are picked up at the origin location as well! Kind of like asking why a supersonic plane traveling at Mach 10 from London to Los Angeles can't be cost competitive when you want to end your trip in Seattle (because you still have to pay a local airline to fly you from Los Angeles to Seattle). So you still have the expense of local freight from source to the tube terminal, and then again from the tube terminal to the destination.
Sure, the tubes would be MUCH faster - but how quickly would that tube capsule of freight be processed and delivered? Would still take a truck 1/2 a day to make the rounds to deliver, so maybe you get it 1 day faster compared to traditional trucking to a terminal, and then local delivery the next day.
With margins under constant pressure, paying that much more for just 1 day's quicker service isn't worth it in most industries. And that's ignoring the massive price competitiveness that trucking has compared to the tubes on a $/lb basis, or $/cubic ft (whatever metric you want to use), even without the local freight handling in the source/destination cities.