I'd love to see some research indicating this is true. While I certainly am used to "weird domains", I still often default to .com when trying to find things. If I want to look at Ford's current line-up, my first instinct would be to try ford.com.
Of course, that fails spectacularly when searching for Nissan cars.
I think there's a certain generational divide at play. If you have only really used browsers with universal search in the address bar, and you've only lived in a time in which the web is commonplace, your attitudes and habits are likely to be quite different. When I first started using the web you had to put the full and correct domain and protocol. Search bars didn't even exist. Habits die hard.
I'm not actually sure if we're disagreeing. Ford only means cars because Henry Ford started a car company. The argument for valuable domains (like milk.com) is that the simple "Milk" brand is more valuable than building your brand around a unique name. Consumers don't care that google is at google.com and not search.com.
I think to some extent when the internet emerged, people transferred the trademark way of thinking into the internet domain. The first dotcom bubble was defined by people pouring money into something they didn't understand. That included spending outrageous amounts on generic simple domains when in fact, time showed that if you had a valid product (eg google, reddit, flickr) you didn't need a simple expensive name to get widespread recognition. Search completely sidelined the strategy that investors were going for - that if someone was looking for something online they'd first try "buy.com" or "pets.com".