The TAB character is not any different from the separator control characters. It is as non human readable as the other ones. It's just that it got more support

The TAB character is not any different from the separator control characters. It is as non human readable as the other ones. It's just that it got more support historically. If e.g. Microsoft had used the separator control characters for CSV you can bet those control characters would have even better support than TAB does today.