They'd just buy it.

Food, for instance. It isn't necessary to persuade people they ought to eat. Hamburger is rarely advertised. Sales on hamburger are – but that's not quite the same thing. People are wanting to buy hamburger, regardless. Maybe they'll buy more if it's on sale. But they'll buy hamburger, regardless.

As far as cars, consider that it is not necessary to advertise heat – or AC. Most people want heat and AC – because it is generally considered unpleasant to freeze in the winter and to sweat in the summer. This is why all cars have heat and AC.

How about all-wheel-drive?

A majority – more than two-thirds – of all new vehicles either come standard with AWD or offer it as an option. Not all that long ago, almost no cars even offered AWD. It was a feature sold chiefly by Subaru and Audi. Now it is sold by essentially every car company.

This reflects the tremendous success selling people on AWD.

But do they actually need AWD? Or is it that advertising has persuaded them they've got to have AWD?

AWD is not like heat or AC in that if you haven't got AWD, you're probably not going to miss it – unless you have to drive on snow-slicked roads as a regular thing. If you live in California or Arizona or another state where winter weather is light – if there's any winter weather at all – then your need for AWD is probably on par with your need for SCUBA gear (assuming you're not a diver). It is nice to have the SCUBA gear, perhaps. But it's kind of silly to have it if you don't really need it.