Arm was a joint venture between Acorn and Apple and another company whose name I forget. It's not unreasonable to think that Apple might have some special benefits due to that.
VLSI Technology. As I understand it, Acorn provided the existing ARM2 chip and its design team, VLSI Technology provided design and fabrication expertise, and Apple provided capital (and the potential for the use of the design beyond Acorn).
VLSI was also the major ARM-based designer / manufacturer at the time, there was almost nobody else building SoC on ARM.