The differential pressure from one end of a gas pipeline to the other is not 1800 psi - it is more like 20 psi. You don't repeatedly recompress along the pipeline length - you compress once at the start, and decompress once at the end.
The reason to use high pressures is because for a given pipe diameter (and therefore cost), you get far more gas transported at high pressures than you do at low pressures.
> You don't repeatedly recompress along the pipeline length - you compress once at the start, and decompress once at the end.
There are often recompression stations in pipelines precisely because pressure drops across the length, and on land it's cheaper to have those along the length of the pipeline than one really big one like NS1 had.
Yes, you do. That is the primary purpose of transmission compressor stations. You may just lose a few psi per mile or something, but over the course of 100s of miles..