You're overthinking it. The average consumer will just read the big text on the package, ask a shop assistant or a friend.
You'll have different sections in shops, "fast charging cable", "fast transfer cable", or "fast charging AND fast transfer cable" (with a price to match)
Or stuff like "supports connecting a TV", etc.
People will understand that there are different cables for different jobs, because they understand that a universal cable will be way more expensive.
> In the old days, you could buy a USB-A to micro USB cable and have it work and charge your phone.
Some USB-A to micro cables charge way faster than others (thicker wire). So this supposedly new USB-C problem is actually not new at all.
You'll have different sections in shops, "fast charging cable", "fast transfer cable", or "fast charging AND fast transfer cable" (with a price to match)
Or stuff like "supports connecting a TV", etc.
People will understand that there are different cables for different jobs, because they understand that a universal cable will be way more expensive.
> In the old days, you could buy a USB-A to micro USB cable and have it work and charge your phone.
Some USB-A to micro cables charge way faster than others (thicker wire). So this supposedly new USB-C problem is actually not new at all.