To start with, it needs to know where you are. Then there is the question of your route—are you taking 80 up to the north side of the lake, or will you take 50 and the southern route? It needs to know what you like. So it will look to the restaurants you’ve frequented in the past and what you’ve thought of them. It may want to know who is in the car with you—your vegan roommates?—and see their dining and review history as well. It would be helpful to see what kind of restaurants you’ve sought out before. It may look at your Web browsing habits to see what kind of sites you frequent. It wants to know which places your wider circle of friends have recommended. But of course, similar tastes may not mean similar budgets, so it could need to take a look at your spending history. It may look to the types of instructional cooking videos you’ve viewed or the recipes found in your browsing history.
And then they want to package all that information all neatly with a bright shiny bow and sell it to advertisers.
Imagine you woke up tomorrow and Google was gone. You would still be able to search the Web. You could still send email. You could still use maps, make phone calls, watch videos, network with friends, write blog posts. There would be a period of adjustment, and it would be incredibly inconvenient but you would get by. There are other options.