It should have been opened in June but was delayed by Trump. Ambassador bridge owner paid money into Trump PAC. It’s all there in the article under History -> Delayed Opening.

In June, The Detroit News reported that invitations were being sent out for a ribbon-cutting ceremony on June 12, with the bridge open to the public shortly after.[96] On the day before the planned ceremony it was announced that the event had been cancelled and that the opening of the bridge was delayed indefinitely to "resolve any outstanding issues".[97][98]. Carney said that the delay had been requested by the United States, and representatives for Trump stated that his position had not changed since February.[99]

The New York Times subsequently reported that billionaire Matthew Moroun (who owns the Ambassador Bridge) had lobbied the Trump administration prior to the announcement.[91][92] The ranking member of the United States House Oversight Committee, Robert Garcia, opened an investigation into Commerce Secretary Howard Lutnick’s earlier meeting with Moroun, sending Lutnick a letter requesting communications related to that meeting.[93] Filings released February 20 showed that Moroun donated US$1 million to MAGA Inc., a Trump-affiliated super PAC, less than a month before Trump's announcement.[94][95]

I don't know the whole story but this happened about 5-months ago.

Trump said in a Truth social post Monday night that he wouldn’t allow the bridge to open “until the United States is fully compensated for everything we have given them, and also, importantly, Canada treats the United States with the Fairness and Respect that we deserve.” Trump suggested the U.S. should take an ownership stake of at least 50% in the bridge and said that U.S. products, such as steel, weren’t used in the construction.

https://www.msn.com/en-us/politics/international-relations/what-is-the-gordie-howe-bridge-and-why-is-trump-threatening-to-keep-it-shut/ar-AA1W4VSa

You wanted consistency? Sure Trump actually did a few things right his first term, but responded to bribes a lot more in his second

Part of the “problem” is the toll is too low. It seriously undercuts the the Moroun Family Bridge tolls so the fear is it will attract most of the traffic. Think of the poor billionaire who somehow bought a bridge

How/where do you do the border crossing paperwork?

So there is a customs/border check