Wow... didn't know anyone even still used coal burners! Probably cheaper than gas or oil right now...
They sell a lot of them, and Ranger's boiler system is pretty new. They're a much better proposition now, convenience-wise, with automatic feed and ash removal.
Even simple stoves sell well; my last stove was a wood or coal potbelly railroad stove, bought new in the late 90s. I mostly used coal in it, except for initial starting wood (and I didn't have to start the coal fire fresh very often), and some occasional scrap lumber and fallen yard branches. Finding, cutting, splitting, carrying and stacking, and carrying again, gets old in a hurry, after the nostalgic romance of burning wood wears off, and buying wood is generally so expensive that it's not worth it. Coal is much easier, and the fire lasts much longer.
No creosote, either, and so no chimney fires, which can get hot enough (up to 3,000 F...the blast furnace/uncontrolled draft effect) to melt the mortar joints in a chimney, and collapse it. Even short of that, they can cause radiation/conduction of an abnormal and dangerous amount of heat through a chimney, into flammable structure, or spew out flaming material onto a roof.
I don't think coal competes with natural gas, at present prices, but it's much cheaper than electric, oil, or propane, which are the other rural choices.