CM: no, people in UK are not at all weird; wired maybe, weird, no.
I understand your point, and I agree that in the cases you cite, one can use singular or plural, according to preference.
However, one in ten is not such a case at all. One is purely and simply one and cannot be construed as a collective noun. One in ten.
Incidentally, I don't think, even in UK, that the majority drive a Ford. That would be quite a few in one vehicle. I could believe that the majority drive Fords, but more likely they drive Minis.