The real problem isn’t alcohol, it’s Butane. You can make hash oil 10x faster using Butane than alcohol. (don’t ask how I know this).
I image the problem occurs because of inadequate ventilation and/or when somebody decides to use a stove directly and not using a hot water bath like a careful person would.
When butane fumes build up, it can easily go off with a flick of a light switch.
Industrial production of hash oil uses a vacuum pot operating at normal temperature. Instead of raising the temperature and creating that danger, you lower the atmosphere and force the boil-off at lower temperatures. This also has the added safety of being able to pump the fumes out of the workshop.
I really don’t follow the “butane”. Chemically useless as far as I know. Also the truck driving I mentioned? I was delivering PROPANE for 25 years, my family was in the business before I was born.
The bottles you see outside the convenience stores, they are all propane, one carbon bond up from butane. They are also underfilled and overpriced. Those cylinders are designed to hold 20# (about 4.5 gal). Look at the plastic; Blue Rhino or whoever is selling you 15# for an outrageous amount.
Only connection I can imagine butane/propane is the heating fuel. We just cooked ours stovetop.