economy is part of it i think, but if they are selling 2 cars and swapping to one car it needs to be practical for both to use, and removing a complete car from the equation makes a huge difference a year.
thats one less lot of insurance, road tax, mot and servicing.
only 1 car to fill up,
so if its only marginally more economical but still fun, you've already made the most of your saving by loosing the other car.
its all well and good people sitting in their zeds telling others to buy a sh1t box; but they're not the ones that ahve to drive it. and live with it etc.