Old ways of doing things often hang on an unexpectedly long time because a mature technology has the advantages of ubiquity. People are comfortable with it, all the kinks have all been worked out, and its popularity gives it a huge structural cost advantage.
You can't think in terms of how expensive it would be to have a 50 lb block of ice delivered to your doorstep today. The *marginal* cost of having ice delivered is nil when everyone on your street is getting it. Everyone had an actual "icebox", and since it had no moving parts it never needed servicing or replacing. So when electric refrigerators became available it was a choice of keeping your perfectly good icebox with its reliable, regularly scheduled ice delivery, or buy a cranky, complicated, expensive piece of machinery that would pay for itself just in time to need replacing. If the ice industry killed itself by shipping polluted ice, it's probably because they couldn't expand their supply to meet demand.
I'll bet the grandchildren of kids learning to drive today will find the whole concept of a massive, truck-based gasoline distribution network absurdly complicated. But it works because it's massive, and because it's ubiquitous we assume it is simple -- which it is on the consumer end. On the production end it is fantastically complicated and labor intensive.
Speaking of the Boston ice industry, I live a half mile from a 20 acre (8 ha) pond that supported a major ice operation in the 1800s. Pictures show men harvesting blocks of ice eighteen, even twenty-four inches thick for shipment around the world. In the non-winter months the companies operated water-powered mills. Ice was a classic case of exploiting slack resources. Ice meant no head for the water powered mill, and an idle workforce. So electric refrigeration wasn't the only pressure on the ice industry: electric factories would have raised the price of winter labor.
Today that same pond never gets more than a couple of inches of ice, even in last year's "polar vortex" event -- you can't make ice that thick in a couple weeks, you need a cold winter that starts early and doesn't let go for months. When I was a kid this pond iced over in December. Now it ices over in Janurary, or Feburary, or some years not at all except for the lee end. In January I can fish from my canoe on ponds where I would once have been ice-fishing.