That is like saying the materials the baker needs to bake bread cost 5¢. Why doesn’t the baker price his bread at 5¢?

That might be a somewhat relevant analogy if you had a choice to go somewhere else to buy bread elsewhere, but since both memory and storage are now soldered, you are forced to upgrade for the lifetime of the product at purchase. The relevance on the parts pricing here is to point out that Apple is being extremely abusive in their pricing to their customers.

Many laptops now have soldered RAM, but other vendors have not chosen to do what Apple has done. In HP's premium laptop (Spectre x360 13t), adding 8GB of RAM is a +$70 option. For reference, an 8GB DDR4 SODIMM at retail pricing is about $30.

Also, AFAIK, no other major laptop or mini-desktop manufacturer uses soldered storage like Apple does, so in this case, the retail cost for storage is even more relevant.

These are commodity parts, so there's not any R&D to recoup - this is just profiteering on Apple's part. Especially for the Mac Mini, where there's not the same space constraints, the lack of storage upgradability is also a rather egregious form of forced obsolescence. Fine from a business perspective, but hypocritical for a company that claims to care about the environment.

Well, no. Apple buys RAM chips at that price, and they just have to swap one chip for another. The differential in price from one to the other including all costs is that much. Labour costs and OpEx are not affected by choosing Chip A or Chip B that are essentially identical.