The Space Shuttle was a far less reliable system from a fundamental design perspective. The size of the wings, the nature of the thermal protection system, the insulating foam and the use of a super-cryogen as fuel, the side-by-side staging, the use of solid fueled boosters on a manned launcher, etc. Engineering estimates show that we were incredibly, incredibly lucky to have the Shuttle safety record we did, the vehicle was a death-trap. We almost lost Atlantis in 1988 and Discovery in 2005 to the same thing we lost Columbia to, and we almost lost several shuttles in the early 80s to the same fate that doomed Challenger.
Of course if an organization ever gets complacent about safety then things can go downhill, but in the case of SpaceX they have a fundamentally more robust vehicle design, a system with more and safer abort scenarios, and every possible reason to maintain a high degree of vigilance about safety (if for no other reason than their company's image and financial bottom line).
Saying "we almost lost Atlantis" only confirms the point that they could have mitigated the foam lost before Columbia, and they could have fixed the O-Rings before Challenger. Not investigating those incidents properly, is a human factors failure.
I do agree that design decisions like side-by-side staging of SRBs wasn't the safest choice. Safer abort scenarios is definitely a feature of Dragon.
One problem i see with spacex is their propulsive landing feature. What if things go wrong at that point, like a software or a sensor problem causing it to descend at a speed too high/not realizing it approaches the surface/just hovering and expending the propelland quickly? If landing on land, they don't have any backup, and astronauts are doomed, falling from even very low altitude (30-50ft) will be fatal.
To some degree that's the case. The Falcon 9/Dragon do very much get a benefit from modern technology. Better machine tools, high-speed digital communications and onboard computers, better material science, the ability to run computer simulations of different flight profiles or to model the operation of a rocket engine, etc. However, in another sense the Falcon 9/Dragon represent very primitive designs. Indeed, 1950s or 1960s designs even. A simple cylindrical 2 stage LOX/Kerosene booster in combination with a simple frustrum shaped manned capsule. These designs have heritage going all the way back to project Mercury.
Yeah, and guns are vastly more reliable than rockets or missiles, too. Sometimes old and simple is the way to have high reliability, sacrificing performance.
Good design does magically appear as time goes by but is a result of a sound design and testing process. Fortunately, I am sure SpaceX is aware of this so they will most likely get a much better track record than the space shuttle.
The B-52 is still a heavily used part of the US heavy bomber fleet and current plans are to keep it in service until 2040 and perhaps beyond (which is longer than the B-1b is planned to be in service).
Of course if an organization ever gets complacent about safety then things can go downhill, but in the case of SpaceX they have a fundamentally more robust vehicle design, a system with more and safer abort scenarios, and every possible reason to maintain a high degree of vigilance about safety (if for no other reason than their company's image and financial bottom line).