Shipping and sorting is not easy on boxes, and most carriers have boxing information on their websites. And unfortunately, many shippers totally ignore them.
Overnight shipping is the hardest on boxes simply due to the speed of the automated shorting machines, and it is possible for a box to loose 40% of it's strength in a single shipment which is why you really should not ship the same box twice in overnight service.
The Maker rails should have been shipped in a stiff shipping tube, but they probably weren't because the tubes are expensive.
https://www.packitusa.com/Shop/C832.aspx
Rocket kits should be shipped in a suitable box that will not crush.
https://www.packitusa.com/Shop/C20.aspx https://www.packitusa.com/Shop/C3724.aspx or at a minimum
https://www.packitusa.com/Shop/C210.aspx which cost between $3 to $12 each. The problem is the buyer is looking for a bargain and the seller is looking to minimize his costs and the biggest cost he has to absorb is the cost of the box.
The bottom line is that if you pay more than $50 for you order, you should buy extra insurance if it is expensive or fragile. If you don't/won't pay the extra insurance charge, be prepared to eat the cost of the item 2% to 10% of the time.
Also UPS, FEDEX and many other common carriers charge more money for unscheduled commercial home deliveries versus daily scheduled business deliveries. To lower the cost to the shipper and the buyer, most small package commercial carriers have a lower cost hybrid home deliver service that delivers to your local post office which makes daily scheduled deliveries to your home. These hybrid services save money, but usually take one day longer than a direct common carrier delivery because the packages usually arrive at the PO after the daily delivery trucks have left the PO. They are no harder on the boxes than a direct common carrier to the home shipping.
Most, but not all, of the damage problems are due to improper packaging by the seller rather than by abuse by the common carrier or PO. That's not to say that the common carrier or USPS are perfect because they're not. Both UPS and FedEx overnight destroyed a properly crated scientific instrument we routinely took to testing facilities around the country. One overnight carrier drove a fork through the crate and another dropped it 10' off an airplane. I've had common ground carriers loose tracked shipments as well. One remarkable loss involved a $2000 empty shipping container that was logged into a UPS transfer facility and never logged out....but it had a rather high scrap metal value.... Another was an explosive shipment that got "lost" in a transfer facility during a blizzard. I had noticed the shipment had not moved in 2 days so I contacted the common carrier and mentioned that I would have to report the loss to a number of 3 letter government agencies if they couldn't located it promptly. Within 6 hours I received a call that it had been located in another facility 500 miles away....and would be delivered the next day to the customer.....