There are two entirely separate customs questions on any hand-carry and people routinely conflate them. The first is about the goods: what they are, how they are classified, what they are worth, who is receiving them and what permits that category needs. The second is about the person: whether this specific courier, on this specific passport, may enter the transit country and the destination country for this specific purpose. A consignment can be perfectly documented and still not move because nobody checked the second question.
On the goods side, the recurring failure is a description that does not support the classification. “Machine parts” is not a description, “samples, no commercial value” is not a valuation, and an invoice that disagrees with what is in the box is the single most reliable way to turn a two-hour clearance into a two-day one. We agree the description, the classification and the value before departure and make sure the consignee's registered details match the paperwork exactly.
Temporary admission is the most under-used tool in the set. Equipment going somewhere to be demonstrated, tested, exhibited or repaired and then coming back should not be imported outright, and where an ATA Carnet fits the category it removes duty and deposit questions entirely. Where it does not fit, there is usually still a temporary admission procedure that is cheaper and cleaner than a permanent import.
Legalisation and attestation are a different discipline again, and one where a courier is structurally better than a parcel: chambers of commerce, notaries, ministries and embassies have counters, queues and opening hours, and the order of the stamps matters. A person holding the folder can move it from one counter to the next in a day. A tracking number cannot do that at any price.


