The mutex case is one where they're using a mutex to guard read/writes to a map.

Please show us how to write that cleanly with channels, since clearly you understand channels better than the author.

I think the golang stdlib authors could use some help too, since they prefer mutexes for basically everything (look at sync.Map, it doesn't spin off a goroutine to handle read/write requests on channels, it uses a mutex).

In fact, almost every major go project seems to end up tending towards mutexes because channels are both incredibly slow, and worse for modeling some types of problems.

... I'll also point out that channels don't save you from data-races necessarily. In rust, passing a value over a channel moves ownership, so the writer can no longer access it. In go, it's incredibly easy to write data-races still, like for example the following is likely to be a data-race:

    handleItemChannel <- item
    slog.Debug("wrote item", "item", item) // <-- probably races because 'item' ownership should have been passed along.