The MD11 in question is a defunct design from 38 years ago. We are building better planes now.
UPS is as old as the plane in question and has only had three fatal accidents in that time with millions of flight hours, most of them on retired airliner frames.
Yes, Boeing had a monumental fuck up with the MAX redesign. However, their last blank page design was the 787 and is seen as completely revolutionary in terms of materials and efficiency. Let’s talk about that plane. It burns 20% less fuel than the planes it was designed to replace, and has a number of incredibly impressive engineering feats purely for passenger comfort- pressurization altitude and window size being the most impressive. It doesn’t sound impressive, but the design ask is: make a lighter plane, with bigger holes in the structure, that can withstand more pressure, and use a material and process that has never been used before. The only fatal incident on the 787 is still under investigation, but is almost certainly pilot error or suicide. Other plane and engine safety technology have allowed ETOPS making it possible to use efficient twin engine jets operate overwater flights that would have been unthinkable 40 years ago.
Jets today are quieter (by such a huge margin that it isn’t legal to operate the original 707 engines at most western airports), more efficient and safer than ever.
In the era that the SR-71 existed in, it was actually pretty common for planes to crash due to design defects (DC-10, Comet, 707, and more). The 737 MAX defect was so shocking because it has been 50+ years since that was common.
The SR71 is a simpler plane in many ways than a modern airliner. The composite technology to build a 787 didn't even exist at that time, and the engine alone on the 787 is far more impressive engineering and material science than the SR71. And there are two companies that figured out how to make them without a blank check from the CIA. The 787 produces more than double the thrust of the SR-71, and most passengers barely are aware of the miracle they are participating.
The SR-71 is an undeniably cool project. I have seen several up close, sat in the cockpit and they are literally awe inspiring. What we build today are airliners that are seemingly boring but built and designed with technology and materials that Skunkworks couldn’t have even attempted.
We aren’t building things like the SR-71 anymore because we are building things that are far better and more complex. We have Lockheed producing the F-22 and F-35, multiple companies reusing space launch rockets, etc. the real problem is that we have lost our sense of wonder at just how impressive modern aerospace engineering is.