Shipping back in the day was a lot more expensive (in real, inflation-adjusted dollars) and less frequent. I am sure some delivery people are careless - but it's also a different industry now, with a lot more contingent and low-paid workers (USPS and UPS are unionized - not trying to start a political argument, but in my experience they also are the most careful with packages - aside from 1 or 2 letters damaged by USPS sorting equipment, I've never had an actual package damaged by either of those companies; and those two companies almost never leave packages outside my house unattended).
Along with the massive increase in volume and time pressure, there's just a lot of stuff shipped all over the place today that was not shipped 30 years ago. There was no eBay or Amazon, and you had pretty much zero average Joes shipping big pieces of audio equipment like they do now. It was almost all done by professional dealers, and occasionally by knowledgeable, very careful hobbyists who packed things very carefully and didn't scrimp on the packing materials. The majority of equipment was shipped long distances only when it was new, and therefore it spent its transit time professionally packed in its original box and custom packing materials, well-secured on a pallet with other similar items, in a professional shipping truck with hydraulic suspension. It would be delivered to a store, and the customer would carefully put it in the back seat and drive it home. After that, it would get handed down or re-sold locally, spending its subsequent "shipping" time on a padded car back seat.
Used equipment a few decades ago simply didn't spend much, if any, time in nonstandard packaging, shoehorned into the back of a local delivery truck with a bunch of other items of varying weight, size, and proportions. And keep in mind that an increasing proportion of our stuff as a society is now getting delivered from Amazon hubs by LaserShip and Amazon Logistics, which use regular cargo vans and sometimes personal passenger vehicles, none of which have hydraulic suspension.