One one hand, the English had really figured out a lot about canal building in the later 18th c., realizing that canals were key to moving heavy commodities like coal and supporting industrialization. They had some quite bright engineers like Thomas Telford, who had some innovative approaches, like using cast iron in aqueducts.

But though canal design was developing in leaps and bounds, the construction of them was, though, still pretty much just with muscle power. There were steam engines: but they were for pumping water ( until Symington put one on a boat in 1803) and would not be used for digging until much much later. Life for these men was about as hard as you can imagine, of course. They were paid by how much they could dig, with a minimum quota. They worked in a rural landscape, mostly, which meant they were housed in whatever hovels they could scrounge together for the purpose and move along to the work sites, if they couldn't get lodging in a farmer's barn.

There's a fun series in the UK called Worst Jobs in History, and they did segment on diggers which is pretty good. Now, it is trying to live up to the title and so it predictably makes things simpler and starker than they could have been. They show a wheelbarrow being drawn up a plank from down in the bottom of a deep ditch, for example, and of course that would not be the way the whole canal was dug, only the lowest cuts. One historian interviewed states that canal workers had one death per mile: one wonders if that was constant, during the simpler digging of the cut through flat fields and deep soil, or whether it was more from occasional riskier procedures like blasting rock, or in doing some tricky tasks like getting the canal over valleys, through soggy or swampy terrain, or through sand. It also has to be seen in context: there were many, many jobs requiring constant physical labor ( farming, for example) and the laborers digging the canal would not be imagining that there was, say, a pneumatic jackhammer and a diesel loader and power shovel available to the crew the next county over. Many people would work very hard to get some small wages, food and beer. Expectations for a better life would not be high. That mindset would also be carried into industrial jobs, which would also often be hard or dangerous. Unions would not exist: indeed, there would be a classic case of rural workers- some shepherds- being greatly punished for trying to organize, the Tollpuddle Martyrs. I do not know about friendly societies among laborers. They existed among farmers: mostly in the early days they would do little more than provide for a decent burial.

Smiles: Lives of the Engineers, v.1