In most of Europe there is no notion of punitive damages in a law suit. That means if you sue that company they will fix the questionnaire with no other consequences. 3 months later they can put it back, also without consequences. Suing them can be costly, so most people will not bother. There is zero reward for doing it, as a candidate you waste time and money with no net return. All negatives and no positives.

So with very little risk, they do it.