In the US, basic utilities like power or water or gas are often handed off to a private company in a local area.

It is understood that these expensive and pervasive infrastructure projects are natural monopolies - it is much more efficient to have one provider than a competitive market. Imagine what a mess it would be if you had several sets of water pipes and power lines running through your neighborhood.

For one reason or another, local governments often let someone else manage all of that. Ostensibly, the tradeoff is that the utility company should be more heavily-regulated than a normal company would be.

But there is also some overlap between areas, and sometimes a handful of competitors are allowed to share physical infrastructure, so in practice it's more like a hodge-podge of hyperlocal oligopolies.