Joanie pointed out that the field in the first example is accessible, but the field in the second is not. <div role='group'><input /> + 1 = 4</div> <div role='math'><input /> + 1 = 4</div> It seems like this could be resolved (treat the math role more like group) without affecting the MathML-specific implementation.
<rdar://problem/49758963>