I've never bought into that reasoning on the automotive side. Selling "one million of this device," as you say, will bring in $20 billion. So yes, they can afford $20K to do the job right.

Also, SMT resistors at that quantity level are more like 1/10 of a cent, not 2 cents, and the PnP machine is running anyway. In fact you often end up using more resistors than strictly necessary, just because the machine holds a limited number of reels and it's cheaper to use more of the same part to arrive at a desired value than to add a new line item.

Things should be as cheap as possible, but no cheaper. Optimizing the cost of individual resistors is almost always a classic example of measuring the wrong thing. We should strive to avoid making excuses for doing that.

If it was purely about saving costs why even use USB-C, though? They could have just said that a 3A micro-usb supply is now required for USB power. The Pi4 isn't actually using any of the increased power delivery provided by USB-C PD, which is in the higher voltage range, after all. It just wants 5V 3A, which micro-usb can certainly handle as well (there are a variety of such power supplies for previous Pi's in fact).

Seems like a really questionable cost-savings maneuver to switch to a way more complicated & expensive connector for nearly no reason, and then penny pitch on one resistor.

Costs taken into consideration sure, but the Raspberry Pi Foundation is a charity, so I'm not sure the same sort of incentives exist on a personal basis. It probably is just the engineering attitude of saving costs as much as possible.

Those small SMD resistors come on a reel, and they're typically much cheaper than 2 cent: more like 0.1 cent. Still, that's $1000 for one million units.