Right, that was an unfortunate choice of words. It's not missing, but leads to (IMO) a proliferation of under-specified text-based data and stream exchange formats.
Having human-readable text as the lowest common denominator is a laudable goal. Shell scripting would however probably be improved if most tools offered alternative typed streams, or something similar. I am not convinced Powershell's approach is the best, but their approach is at least interesting.
Picking nits, but the decision to use plain text as the common data format in Unix does not rule out structured text (e.g. CSV, TSV, XML). Nor does it imply “human-readable.”
The original decision was about not proliferating specialized or proprietary binary formats, which was more of a norm back in the ‘70s than today. The goal was to make small single-purpose tools that communicated through a common interface (files) in a standard format (plain text). Unix succeeded and continues to succeed at that.
Nothing about those design decisions precludes tools using binary formats under Unix — image processing, for example. It just precludes using standard text-oriented tools on those formats.
Having human-readable text as the lowest common denominator is a laudable goal. Shell scripting would however probably be improved if most tools offered alternative typed streams, or something similar. I am not convinced Powershell's approach is the best, but their approach is at least interesting.