That is completely the wrong way to think about it. Before the Great List Refactor those were dealt with the same by most operations (as you apparently want it). And that was the absolute biggest problem that needed to be changed at the time. There were things that just weren't possible to do no matter how I tried. The way you want it to work DID NOT WORK! It was terrible. Making scalars work as single elements was absolutely necessary to make the language usable. At the time of the GLR that was the single biggest obstacle preventing me from using Raku for anything.
It also isn't some arbitrary default logic. It is not arbitrary, and calling it "default" is wrong because that insinuates that it is possible to turn it off. To get it to do something else with a scalar, you have to specifically unscalarify that item in some manner. (While you did not specifically say 'arbitrary', it certainly seems like that is your position.)
Let's say you have a list of families, and you want to treat each family as a group, not as individuals. You have to scalarize each family so that they are treated as a single item. If you didn't do that most operations will interact with individuals inside of families, which you didn't want.
In Raku a single item is also treated as a list with only one item in it depending on how you use it. (Calling `.head` on a list returns the first item, calling it on an item returns the item as if it had been the first item in a list.) Being able to do the reverse and have a list act as single item is just as important in Raku.
While you may not understand why it works the way it works, you are wrong if you think that it should treat lists-of-scalars the same as lists-of-lists.
>> This attempt to fuse higher-order functional programming with magic special behaviors from Perl comes off to me as quixotic.
It is wrong to call it an attempt, as it is quite successful at it. There is a saying in Raku circles that Raku is strangely consistent. Rather than having a special feature for this and another special feature for that, there is one generic feature that works for both.
In Python there is a special syntax inside of a array indexing operation. Which (as far as I am aware) is the only place that syntax works, and it is not really like anything else in the language. There is also a special syntax in Raku designed for array indexing operations, but it is just another slightly more concise way to create a lambda/closure. You can use that syntax anywhere you want a lambda/closure. Conversely if you wanted to use one of the other lambda/closure syntaxes in an array indexing operation you could.
The reason that we say that Raku is strangely consistent, is that basically no other high level language is anywhere near as consistent. There is almost no 'magic special behaviors'. There is only the behavior, and that behavior is consistent regardless of what you give it. There are features in Perl that are magic special behaviors. Those special behaviors were specifically not copied into Raku unless there was a really good reason. (In fact I can't really think of any at the moment that were copied.)
Any sufficiently advanced technology is indistinguishable from magic. So you saying that it is magic is only really saying that you don't understand it. It could be magic, or it could be advanced technology, either way it would appear to be magic.
In my early days of playing with Raku I would regularly try to break it by using one random feature with another. I often expected it to break. Only it almost never did. The features just worked. It also generally worked the way I thought it should.
The reason you see it as quixotic is that you see a someone tilting at a windmill and assuming they are insane. The problem is that it maybe it isn't actually a windmill, and maybe you are just looking at it from the wrong perspective.