My experience is mainly limited Northern Europe. My knowledge about US is severely limited (really brief small talk when having visitors over). Take this into account.

For me a port is a region with multiple terminals. Each terminal could have a different owner, different container ship companies going to it, etc. The port itself usually takes care of the land (incl. concrete.. those quay cranes need a lot of support), etc.

From what I understood, most things in US is done using trucks whereby other parts of the world might use something else like e.g. a straddle carrier ( https://en.wikipedia.org/wiki/Straddle_carrier). That's one reason for the trucks. Meaning: not only to pick up or to deliver a container, but also used in the terminal operations itself.

Most important point in Europe is the early morning rush. A city might have limitations on when trucks can arrive. Usually companies want their goods early in the morning so they ask the trucking company to deliver it early in the morning. Then they unload the container during normal working hours.

For pretty much everyone (port, terminal, trucking company) that's terrible, because you don't use the infrastructure in an efficient way (it needs to handle the worst.. unused capacity = waste of money). But a terminal cannot really influence this, else they're at a competitive disadvantage vs other terminals. It needs to be agreed on a port level.

For pickup/delivery you need the gate to be open. A terminal might work 24/7, but they can restrict when their gates are open.

Take the terminal from the article:
http://www.apmterminals.com/en/operations/north-america/los-...
"Mon - Fri 07:00-17:00 (1st shift), 17:00-02:30"

Take a European terminal from same owner:
http://www.apmterminals.com/en/operations/europe/rotterdam/i...
"Sunday 15:00 - Saturday 15:00 open, Saturday 15.00 - Sunday 15.00 closed"

Meaning, during the week you can pick up your container whenever you please. That LA 07.00 opening time is late; truckers seem to be night/early morning people. Further, the 07.00 might then conflict with people going to work.

Ideally what you want really flexible gate opening times (work week.. way less demand during weekend) plus to give truckers a slot when they can pick up containers. Often containers are stacked on top of each other. If truckers arrive randomly, they might want the container that's underneath 2 others. That cost time and is just wasteful. If you give everyone slots, you could slot (or stack) them in the order they pick it up (first slot at the top).

IMO the entire efficiency is a bit like programming but without the convenience of improved CPU's.

Regarding the union bit: any terminal in Europe big enough to work 24/7 works 24/7. In US I heard they usually stop during the night (which to me is insane). For a shipping line, the quicker a vessel is in&out of the port is usually cheaper than the additional cost of having people work during the night. Lots of somewhat unskilled people make an impressive amount of money (also due to the risks involved). I heard (again: no clue and based on 2 min conversations) that unions block this. This while it is common practice anywhere else. Being European I thing unions are a good thing, but IMO US unions aren't unions.