If they're used to R, MATLAB, or basically any statistics programming/scripting language ever, not only will they be expecting 1-based indexing, they might not even know that that's a thing they have to think about.
The truth of the matter is that this is not a point that anyone should ever mention as either a pro or con of any language. It's simply a fact that you're going to see one or the other, and it's useless to complain about which one is present in any given language. It's a one-time discovery as to which you're working with. People try to make it out to be a debilitating factor, when in reality it's a non-issue.
The problem doesn't just go away with for each style loops. Python added enumerate for this reason but it really is quite clumsy for anything more complicated (and you have to choose if it's indexing from 0 or 1 anyway).