Almost every logistics tool ever built assumes an industrial estate: a numbered unit, a level concrete apron, a dock at deck height, a goods-in office with someone in it between nine and five. Horticulture has almost none of that, at either end of the journey.
The despatching nursery is up a farm track. The receiving garden centre takes deliveries through a service gate round the back that isn't on any map. The landscaper's site is a field with a gate reference and a mobile number. The grower buying your liners has a yard you can only reverse into if you know to swing wide at the barn.
So the last two kilometres get improvised, every time, by whoever happens to be driving. Improvisation is fine right up until the moment it isn't. Then a full trolley of living stock is standing in a lane, the phone is going unanswered, and everybody involved starts losing money because nobody ever wrote down how to get in.