Traditional surveys ask people to declare their opinions. People answer as they wish to be seen, not as they instinctively feel. This is known as social desirability bias. No amount of questionnaire design eliminates it — it is structural.
Implicit Association Tests partially address this by measuring reaction time as a proxy for instinctive association. But IATs are designed for binary comparisons, require laboratory conditions, and cannot be deployed at population scale.
Every existing system that collects individual-level human behavioural data operates within UK GDPR personal data scope. This creates consent requirements, data governance overhead, and liability that many enterprise clients are unwilling or unable to absorb.