A large part of cables is patents, licensing, research and R&D. All those costs don't have to scale with the number of cables produced.

That doesn’t mean the cable that can will cost $30

Considering the way the middle of the market (for lots of products, not just cables, and not just electronics) seems to evaporate and the options become "cheap and shitty and may not work at all", "mid-priced but still shitty", and "actually built correctly and will actually survive normal use but way more expensive than it seems like it should be, thanks to a combination of economies of scale and price discrimination" I wouldn't be surprised if a full-capability USBC cable that doesn't break the first time you unplug it "wrong" or trip over it, and doesn't glitch out or fail to work correctly in some situations, and is of a useful length, does end up around $30.

GP didn’t say they’d cost the same. They said $30 is too expensive