Quoted from DCFAN:
If Dutch Pinball wanted to become a regular pinball company rather than just making one game, they really needed to set up their own factory.
That sounds great in principle, but in practice there are a ton of costs and issues involved with running a manufacturing facility that are better handled by someone who specializes in it. CMs will have better access to parts sources, volume discounts and expensive equipment that they can amortize across multiple clients versus you as a single entity could not afford.
Going the CM route was a smart play for Dutch, but it's unfortunate that they chose the wrong manufacturer to do it. I gather ARA is mostly making medical equipment and there are unique issues with pinball manufacture that perhaps they didn't understand or foresee.