Our Constitution was not a proclamation written by a convention. It was a negotiated contract for uniting thirteen sovereign independent states. Nothing like that had ever been done voluntarily, and few nations have matched it in two hundred years, even with the use of force.
Passenger trains of Europe are often praised as superior to our own. There are some bullet trains that go faster than any American train, and there are examples of trains which arrive more promptly than ours do. Mostly, Europeans have more train traffic than we do, so service is perceived as better. More serious European defects are less easily noticed, however. For example, the width between tracks varies between different nations can vary a great deal, causing a stop to change the wheels as you travel between nations. The disruption at the border between France and Spain is particularly notable, and between former Communist countries and capitalist ones. Even between the Netherlands and certain neighboring countries. Still less noticeable are differences in nuts and bolts, electrical wiring systems, and the threads of screws. If notice is taken, a tourist is offered the explanation that this dates to earlier concerns about invasions, Blitzkrieg and the like. Quaint.
The section on Patents and Copyrights is the only clear example in the Constitution, suggesting uniformity is innately a good thing to encourage. It conflicts with absolute liberty, a little, but it discourages needless individualism when that causes needless friction.
The only overt passage in a document which seems to express a preference for national standards is the clause creating national patents and copyrights. After all, the Constitution would have to be ratified by state legislatures, who might take offense at being criticized for deliberately inconveniencing the citizens with incompatibilities between local products and imported ones. But the preference for national uniformity was clear enough from this one implicit prohibition of state latitude, combined with liberal quoting of Madison's views of how citizens could discipline despotic state government -- by moving their residence to a more enlightened state. You don't move to Wyoming because of nuts, bolts, and screws, but you can dis-elect your local legislator for doing something the Founding Fathers frowned upon. And, as Mr. Dooley is famous for saying, the Supreme Court reads the newspapers. Corn is corn and eggs are eggs, but the Industrial Revolution provided many more opportunities for sharp behavior of this sort than a rural nation would provide. And by being new and novel at the time, deliberate nonuniformity was easily noticed, and all the more irritating.