And is not just software. Reducing an entire computer room to the palm of your hand but with better storage, graphics and computing power is basically black magic. I can't imagine what Voyager could do with a current Nvidia chip.
2) Just because people is not trained in some specific domain does not mean that they couldn't be motivated to do it. I bet that the people that built the Voyager didn't born with the instructions engraved in their brains. And if they learned, other people can also.
If I learned something after lurking HN for a lot of years is to never, ever, underestimate this community. This place stills keep surprising me in good ways.
Since then, we had massive advantages in manufacturing. Maybe COTS parts aren't as usable in space as they were back then, but we can now easily manufacture something more resilient or, as a fallback, simply use those old parts. Also, basically all current electronics are designed to be and are used on earth ~100% of the time. Over-engineering it for use in space is just a waste.
Why? Deep space radiation is only 4x the dosage compared to LEO. Starlink satellites use modern tech and they've spent >10,000 collective years in space since we launched more than 2 of them. The whole "modern electronics are more fragile" issue is overblown. The CPUs are tiny and easy to shield. The MMICs use huge features that you can see with a normal microscope.
"Modern electronics are more fragile" issue really is not overblown. One of my peers have tested different types of non volatile memory in LEO and the TLC NAND sample gets totally wiped by ionizing radiation within the first week. CPUs, while being mostly logic and less susceptible to low energy events, can still be easily destroyed especially if radiation causes latchup. MMICs and discrete devices have huge features in comparison yes, but the junctions still degrade notably under radiation.
From my opinion as someone working on LEO satellite hardware, it's easy to have opinions about stuff like correctness and reliability because it is not naturally intuitive and usually requires observation of many samples over a long time that it doesn't affect most engineers. However, I've definitely seen a strong correlation between the effort spent on correctness and reliability, and the success of missions.