Those can certainly be barriers but it's not the same argument as arguing there are "food deserts".
(Edit: perhaps misunderstood what you were referring to, but if a food desert is say 10 miles without access to fresh groceries, not having a car makes that much more difficult. Even with a car, that means a larger time commitment. So I see that as part of the reasoning of what a food desert is and why that is a barrier to access to healthy food.)