I agree with “… Immigration officers and consistency do not go hand in hand.”. But that is because really each person, each case is is somewhat unique.
True, immigration law is rather explicitly defined as to what situations are legal for entry and which ones are not.. and further, under each type/class of entry, what are the specific conditions for said type/class.
Where *I* think sometimes things go a bit off track is rooted in the fact that while an individual officer can’t essentially create their own law as to you’re admissible or not, they DO have the right to question and request any documentation they deem reasonable to ascertain that you meet the requirements in full.. Essentially the burden of proof falls to you to prove you’re eligible … Immigration really does not have the burden to DISprove your eligibility.
Of course, to be extensively questioned is never a positive nor enjoyable event - but in the end, it’s just a part of the process ... and a part that does allow for officer discretion in terms of scope, depth, breadth and such as far as questioning goes.