Lawyers are subject to ethical requirements that are not imposed on non-lawyers. And those ethical requirements are just that - requirements. If a lawyer breaks them, they jeopardize their entire careers. There's no equivalent for a professional CEO. Clients insist that their attorneys act in a fiduciary capacity.

This is very different from the chip engineer scenario. It is the most important reason why non-lawyers are not allowed to own law firms. Because non-lawyers are not bound by rules that require them to put profit motives second in many circumstances.