[progbits]

Point isn't to save BOM cost, margins are high already and they can eat into them.

Unless they are making literally less than 10 of those, custom board will be easier to manufacture than that mess of dev boards and more reliable than random wires and headers all over the place. Plus they can spend money where it makes sense, using better regulators etc.

[thereisnospork]

Only if you happen to have the relevant skill set.

Speaking as someone capable of designing the mechanical hardware and who is broadly electrically savvy but who is most definitely not an embedded engineer: I could bang out a few hundred hacked together dev boards in week, but doing a custom board would take me a few months. Starting with reading 'Prototyping PCBs for Dummies'.

[mrheosuper]

or just hire a guy that knows how to do their job.

[progbits]

Also it's actually simpler than it might seem, especially if you are not doing anything high-power or high-frequency (which, again, if it's a bunch of breakout boards connected over 0.1inch headers they clearly aren't).

Watch a few YT videos, copy-paste the reference schematics for all those boards, delete what you don't use and you are almost done :)