"Considerably more complex" is probably underselling it. A fully capable port has a withering array of signaling standards to support, as well as supporting very high data transfer rates. It's a seriously challenging port to implement. Not something where you can buy a $2 chip and support a dozen ports like USB2.
Even setting aside the electronics, the physical socket is an order of magnitude more expensive. A lot of budget phones still use MicroUSB purely for cost reasons, because that $1 of BoM cost can be better used elsewhere.
Gamer's Nexus Youtube channel recently did a tour of Shenzen and produced an amazing "How it's Made" series on the components making up the majority of a modern gaming PC. One such video covers USB-C cables, here:
Titled: Why USB3 Type-C Isn’t on More Cases | How Cables Are Made Factory Tour
In brief - the cables are way more complicated, with many very thin cores. To the point they require manual labour from people in a lot of spots where simpler cables can be automated. Therefore slow to produce and expensive!
