And people aren't even always very honest and/or open with motivation.
For people’s motivations which are influenced by social surroundings, experiences and ideologies etc. it doesn't always mean that they're lying about their motivations. They genuinely believe that the reasons for their actions are their real motivations.
Motivations for things that happened in the past change (probably for justification for acting weird in the moment) depending on how you feel in the moment you looked back. This change could be related to the fact that your hungry, tired, woke up feeling like shit or your girlfriend dumped you 2 days ago.
Socionics tests observe peoples motivations at one instant of time (when the test is taken), so they are subject to being screwed up by social surroundings, experiences etc. problems and in the moment problems.
When you know someone and observe them, you see them in different states (moments) and you can generalise their behaviour, so you can get over the in the moment problems but you still can get screwed by the social surroundings, experiences etc. problem.