Why would you have strings that are not supposed to be human readable? Machine to machine should ideally use bytearray (b""-strings) or integer enums for that purpose.
Then you also have the ambiguity of what is considered human readable, is an xml document human readable? Http headers? File paths? Urls? Is a programmer considered human?
I believe the point is whether the string is intended to be displayed to a human, not whether a human might read it in the code. Still some wiggle room around logging, etc. I guess.
Sorry if i wasn't clear, what i meant was actually why would you have strings that are not intended to be displayed to end user?
Smells like non binary serialization format or something alike, which is usually a code smell. It's convenient the first 2 weeks but once the project grows you need a more strict schema and once you have that you might as well use a serialization library which might as well have a binary serialization backend.
Colors as strings is a perfect example of what i'm trying to question here. How do i know which colors that are valid? Run time error? No thanks. Reading online documentation[0]? No thanks. I'd rather have my auto-complete[0] tell me right away the available options and my compiler tell me if i misspelled 'turquoiuse'. A better solution for this is a color-class with a long list of predefined colors as constants, and since they are just constants they could have any underlying format, not necessarily a string. Even in a dynamic language such as python this should be preferred over random strings.
Then yes, there are valid uses, especially in ad-hoc scripts. Column names and dictionary keys are one of the gray zones, though again, in my experience once your project grows these are also usually better to code generate from your db schema or serialization protocol; either complete data structures, api-functions, or just a list of constants. Anyway, my point is not to ban strings entirely, it's to question what we use it for. If you use strings as data/identifiers so frequently that you need a special convention for them something smells quite fishy.
[0] Auto complete = More accessible form of documentation. Before someone starts screaming that i'm stupid for "ignoring documentation".
Then you also have the ambiguity of what is considered human readable, is an xml document human readable? Http headers? File paths? Urls? Is a programmer considered human?