What does it mean to say that "there are no frequencies" in quantum mechanics? A footnote to the introduction to Tim Maudlin's Quantum Non-Locality and Relativity says:

The many-worlds theory is incoherent for reasons which have often been
  pointed out: since there are no frequencies in the theory there is
  nothing for the numerical predictions of quantum theory to mean.

Setting aside for the moment the validity of the conclusion of this statement, what does the premise that there are "no frequencies" mean? 
Does it simply mean that the squared amplitudes of quantum theory do not correspond to frequencies; that is, its not the case that there if the probability of one measurement outcome is twice the probability of another, that there exist twice as many of the former "worlds"?
 A: There are several interpretations of probability, including a frequentist interpretation. On this view we define the probability of an outcome obtainable in a reproducible experiment as the $n\to\infty$ limit of the fraction of $n$ such experiments in which the outcome occurs. (Of course, any "the probability is $p$" claim implies such a result if experiments are independent; but frequentism defines probabilities in terms of the observable frequencies, so that if we can't indefinitely repeat a trial there's no such thing as "probabilities" to describe its outcome, merely whether one thing happened or another.) But when we calculate a quantum-mechanical probability, we consider only the current state of one system. Our ability to compute $|\langle\phi |\psi\rangle|^2$ depends only on understanding the Hilbert space's inner product and which vectors in the space describe the current and hypothetically observable state; there is no discussion of whether the experiment can be repeated with arbitrarily many identical setups.
