I'm pretty sure the gas companies he is talking about from the 19th century covered different portions of the city and had gentlemen's agreements (that occasion

I'm pretty sure the gas companies he is talking about from the 19th century covered different portions of the city and had gentlemen's agreements (that occasionally broke down) not to muscle in on one another's territory - similar to gang warfare dynamics. Thus even in the beginning they effectively had a series of mini monopolies which overlapped a little, causing 'zones' of competition. The point that flew over mises head was that this was an unstable arrangement that provided the competition that proved beneficial for a time to consumers, but eventually such situations 'stabilize' and a clear winner emerges who can basically impose a tax on everybody and collect enormous profits in the process. Mises just sort of pretends that the last part never happens unless a government steps in to force it to happen. Which is rubbish - you can easily use economies of scale and predatory pricing to drive smaller competitors out of business in such industries.