As a ref, the decision will be made by the official who has the better credibility in the situation. It might look as though the ref is leading the decision but that isn't the case. As mentioned above, they lead one another into a decision with discreet signals before raising arm/flag, and with the comms systems that EFL officials have, they also speak to one another. Even if it looks that way, it shouldn't be assumed that the assistant referee isn't making the call.
Also, as fans I'm sure we'd rather them take a second and look this way than have the ref signal one way and the assistant contradict him, it would cause many more problems to the credibility and match control of the officials.