successful train lines in Japan are all built between CBD and some spots / attractions. Odakyu: odawara / hakone, Seibu: chichibu, keiou: Takao, toukyuu: Nikko / kinugawa, nankai: Takao.
Tourists spots are usually in the mountains and the CBD is near the sea. And residential area is developed between them along the lines so the trains carry bidirectional passengers to work or relax on the same line, higher utilization keeps ticket fare low.
Not only encoding/decoding but searching and sorting is also different. We may also cover font rendering, unicode modifiers and emoji. They are so common and fundamental but very few understand them.
I think it depends on what you're compressing. I experimented with my data full of hex text xml files. xz -6 is both faster and smaller than zstd -19 by about 10%. For my data, xz -2 and zstd -17 achieve the same compressed size but xz -2 is 3 times faster than zstd -17. I still use xz for archive because I rarely needs to decompress them.
Tourists spots are usually in the mountains and the CBD is near the sea. And residential area is developed between them along the lines so the trains carry bidirectional passengers to work or relax on the same line, higher utilization keeps ticket fare low.