Large Cabinets ...
This is a large trunk with a large cabinet with drawers.
When a tack trunk is placed on top of a cabinet, there is an opportunity to store twice as much equipment while taking up the aisle space for just one trunk.
Also, if you travel to shows, things that you do not need for that event can stay in the cabinet - extra tack, winter blankets, special bits, etc. - making operating out of your trunk way easier.