While that is true, smaller gives the potential for some cost savings.
Thinner means less frontal area, less drag, meaning a smaller battery pack is possible,
Shorter combined with thinner means less raw materials, less weight, and the potential for a smaller battery pack.
Smaller means wiring harness runs are shorter, with less copper and again less weight.
Smaller and lighter means smaller motors, combine this with smaller wheels, again less weight.
To be cheap it would need an LFP battery, and perhaps some other design compromises, and material choices.
It is certainly possible to make a great performing small car, and that isn't necessarily going to be cheap, II agree that small car can be expensive, especially if stellar performance and long range are the design objectives.
A small car designed to fit a budget might not have stellar performance and long range, it is likely that there are compromises in these areas.
My attitude to the $25K car is simple - whatever it takes - price is important here, more important than any other consideration, except perhaps for a floor in terms of quality, performance and range that Tesla will not go below.
To build a $25K car, it has to be designed for that price point, the mission has to be pursued, with vigour and no stone left unturned, failure isn't an option.
The mission dictates that in this case Tesla hits the price point, and still makes a reasonable margin on each car.
it is important not to rush it, do it once, and do it right.