I live right near a canal that was completed in 1832, and it was essential and a massive success.

Many people know the story of Canada (or Britain and its North American colonists) burning down the White House. It wasn't just the White House though, it was a bunch of public buildings in Washington including the White House, the Capitol and the Washington Navy Yard. What people don't know is that this was in retaliation for the Americans burning and looting York (today's Toronto), which was at that point a small town and the capital of the province of Upper Canada. The Americans broke the laws of war when they did that, so there was a temptation to do the same to them in Washington, but cooler heads prevailed and only the public buildings were burned.

After the war of 1812 ended, the British realized how vulnerable Canada was to the Americans. In particular, the only way to ship things from Montreal to the strategically important towns to the west (Kingston, York, etc.) was down the Saint Lawrence seaway, and the Americans controlled the lower bank of that route. As a result, the British decided to build the Rideau Canal, so goods could be shipped from Montreal to Kingston (and then from there onto the Great Lakes) while avoiding the choke points on the St. Lawrence.

The Canal was finished in 1832 and it was a huge success. Not only did it protect Canadian shipping from a possible US attack, it also avoided all the rapids, etc. on the St. Lawrence. For a few decades it was the main way to move goods and people west, allowing for areas to the west of Montreal to be settled. Canada's capital, Ottawa, wouldn't exist if it weren't for the Rideau Canal. Kingston, at the mouth of the Canal gained a lot of economic significance because of the Canal and was a unified Canada's capital from 1841 to 1844. And Toronto was settled by people moving through the Canal, it nearly doubled in size between 1832 and 1834.

By the late 1850s, a railway was built between Bytowne / Ottawa and the St. Lawrence, and this railway was used instead of the canal. But, the demand might not have existed for the railway if people hadn't been able to move west thanks to the canal.

It may be that people saw the success of that canal, and of other important canals, and that there was an overbuilding as a result of that. And, that when the railways came there was a more effective way of doing some of the same things. But, canals were incredibly important for a few decades and shape the world we live in now. So, how dare you compare them to AI datacentres, you jerk.