Why do competing businesses (e.g., gas stations) so routinely situate themselves in close proximity with each other?

I think someone tried to explain this to me before, but I don’t remember being satisfied with the answer. I’d say the business world is my least knowledgeable area (aside from sports), so I’d appreciate input from those who may have a better understanding of business. With gas stations especially, people (at least I) usually just go to any convenient (or inexpensive) station when they need to fill up, but so often, I see 3 gas stations at one intersection. Often times, they are situated in such a way that 2 or more are even equally convenient for the same lane of traffic. As a non-business-expert, I’d naively assume that such a decision would be bad for business and cut down on profits, as they’d be shared with the neighboring stations. Can anyone explain how this situation is desirable for businesses?