And there’s already a way to drive across it; the Tacoma Narrows Bridge and the Hood Canal Bridge.
This has already been pretty well covered in this thread, but bridges aren’t just about what you can see. Conditions under the water dictate what you can build. Just east of Seattle is Lake Washington. It’s only a mile-and-a-half across, which isn’t all that far. And most of the boats are recreational, so you don’t need a very high span. The problem is under the water. The lake is 200 feet deep, and at least a hundred more feet of soft soil before you get to a solid bottom, so any sort of bridge pilings aren’t going to work. The solution is a floating bridge which is anchored in place by cables. it works really well, right up until it doesn’t.
When I moved to the East Coast, I decied to rent a truck and pack everything myself. My route took me over the Mackinac Bridge. I’m generally okay with height and bridges, but the seating position in the truck was higher than cars and even SUVs. It was a little disconcerting to be up so high and not see the guard rails in my peripheral vision.