I know there are very likely programmers that are gleeful about it, but I suspect that many of the gleeful voices we hear online are not programmers and are resentful of that fact

I see this a lot with the type of people who are making AI "artwork". They often lacked the discipline to practice and learn to make art themselves, they seem to bear an underlying resentment to people who do make art. They are the sort of people who think making art is tied to some innate talent and not something that you can practice. Now they are gleeful about AI generators because it lets them create the pictures in their head without the effort of learning a skill, and they are celebrating that they no longer suffer under the tyranny of people who actually enjoy drawing and painting

cash was and is still instant.

When doing large enough transactions that makes cash cumbersome, the slowness is a feature not a bug. We would want multiple reviews and time before it settled.

The value of $100 bill was much higher in 2000 and in 1969 when it became the highest denomination in circulation, so you could transact much higher value with a “wad of cash” than today.

Before 1969 we had bills up to $10,000 for a reason, they served like a credit note/T-Bill from the government, they were no longer needed after banking became robust enough for Cheques/P-Notes etc to replace them.

Paper Cash or Gold/silver coins before them are well understood solved problems, with thousands of years of experiments on size, security ,seigniorage and so on.