Why does training data carry no machine-readable record of whether anyone consented?

The legal question of whether AI training requires consent is largely settled, courts and regulators say it matters. The practical question of how a consent signal travels with a piece of text through the crawl, deduplication, filtering, and mixing stages of a dataset pipeline has no answer. Robots.txt is binary and coarse, applies to crawlers not trainers, and is routinely ignored by closed-source pipelines. The EU TDM opt-out under Article 4 of the DSM Directive has no standard machine-readable format that a pipeline can verify at the item level. The 2025 Data Provenance Initiative audit found pervasive missing and ambiguous consent signals across major training datasets, meaning even a builder who wants to respect consent cannot technically do so because the record is not attached to the data.