Military allies provide a sense of stability.

Trade Agreements usually have processes to resolve international company disputes and dealings with companies in countries without an agreement can be a costly legal exercise.

It's not just trade, this stability offers US companies opportunities to partner with international companies on specific ventures which obviously requires a lot of trust since billions of dollars are often at stake.

I don't know if the USA develops military alliances specifically for trade or if its developed alliances with major trading partners but a huge number of its top 30 trading partners are also military allies.

Again, I'm not saying that I agree or disagree whether this is all the right way or best way to operate. I'm just saying that I have no idea what the cost to US companies and citizens would be if the US were to drop all its military alliances.