Equality vs. Equity

> What if Sally lives close to a grocery store and Dave does not. Sally could walk to get her groceries on her lunch break, but Dave has to drive or take public transit, which is an additional expense.

But how does this play out in practice, where you don't know how far a random customer or employee lives from a grocery store? Do you use some visible characteristic as a proxy measure instead?

And would you still call it 'equity' if you used that proxy to measure not just need, but also ability, or indeed any other characteristic?