Edit 2: The previous title of this question was "Why are qubits bosonic?" Thanks to the answers that have been provided so far, I now realize I asked my question in a sloppy way. The question I would actually like answered is something more like "Why can local spin-1/2 degrees of freedom in condensed matter systems be chosen to commute, in light of the spin-statistics connection?" What follows is the original body of the question.
I have a very simple, probably even trivial question. In the condensed matter literature, I see local qubits referred to as bosonic degrees of freedom. Now, a qubit is a spin-1/2 system (or at least can be realized by or mapped to such a system), and at least in relativistic QM, spin-1/2 particles are fermions. So why are qubits bosonic degrees of freedom?
One thought I have is that in condensed matter, there's no Lorentz symmetry (at least microscopically), so there's no spin-statistics connection and hence no requirement that spin-1/2 particles be fermions. Perhaps we just get to choose their exchange statistics as we wish.
Another thought I had is that since we are considering qubits on different sites of a lattice, the qubits are distinguishable, hence they commute and we treat them as bosons. But since the boson/fermion classification applies to indistinguishable particles, I think this is probably not it.
Edit: Here are a couple examples of what I'm talking about.
In Ref. 1:
An example of local bosonic model is given by a spin 1/2 system on a lattice.
In Ref. 2:
The first bosonic model is a spin-1/2 model on a d-dimensional cubic lattice.
[1] A. Hamma, F. Markopoulou, I. Prémont-Schwarz, and S. Severini, Phys. Rev. Lett. 102, 017204 (2009), arXiv:0808.2495
[2] M. B. Hastings and X.-G. Wen, Phys. Rev. B 72, 045141, arXiv:cond-mat/0503554