I wouldn't necessarily agree with your characterization of it. It is very well known in behavioural research that people often do not have insight into some of their own behaviours: for example, if you ask people how much they smoke, how much they drink, how many vegetables they eat, you'd typically get responses that do not reflect the actual behaviour. Depending on the context of the work you're doing, sometimes it's important to find other indicators that are more reflective of the behaviours you're interested in.
For example, in voting a lot of times people will say they're unsure as to how they're going to vote. That doesn't mean they won't have a consistent voting behaviour; it just means that at the time they haven't thought about it and they're not necessarily going to give you a helpful answer. If you can find other indicators of that, that's all that means. There's nothing nefarious about it.
I can guarantee that every party in Canada does modelling projects that look for indicators in voting behaviour.