This sentence:

In the desert, gas stations are few and far between.

means that there are few gas stations in the desert, and there is a lot of space between any two gas stations. In other words, there are few gas stations and they are widely dispersed. Far between refers to the distance between the gas stations.

This sentence:

In the desert, gas stations are few and far between.

means that there are few gas stations in the desert, and there is a lot of space between any two gas stations. In other words, there are few gas stations and they are widely dispersed. Far between refers to the distance between the gas stations.

I'm a native speaker, and I found this expression confusing for many years. But it does make sense.

This sentence:

In the desert, gas stations are few and far between.

Means that there are few gas stations in the desert, and there is a lot of space between any two gas stations. In other words, there are few gas stations and they are widely dispersed. Far between refers to the distance between the gas stations.

This sentence:

In the desert, gas stations are few and far between.

means that there are few gas stations in the desert, and there is a lot of space between any two gas stations. In other words, there are few gas stations and they are widely dispersed. Far between refers to the distance between the gas stations.