Pick three tech companies at random: one large, one medium, and one small. Make sure that at least two of them are on the Peninsula (say, San Mateo or Mountain View.)
First, try to get to them by public transportation.
Then, another day, rent a car and try to get to them by car.
Good luck as you decide whether to come to the Bay Area!
Some people figure out how to make do with only public transportation and a bike, but that severely limits where you can live.
Most people drive, and those who bike or use public transportation either have a car, or live in a household where they can use a car. (1-car couples, or borrow a roommate's car.)
Case in point: I took a job in San Francisco, where they told me that they were moving to Menlo Park, but a few blocks from the Caltrain station. At the time, I lived a few blocks from the Palo Alto train station. For my first month, I took the train into the city and biked to the office, which worked about 95% of the time. (I drove when it rained, or when I had to go somewhere after work.)
Later, when they moved to Menlo Park, it was a short 10-minute bikeride, so I continued to ride my bike, except when it rained, or I needed to go somewhere after work, or when I was recovering from surgery. When I met my wife, I started biking through Stanford to sleep at her place after work.
BUT: My wife and I had to move further away, and then my job moved further away, and I was no longer able to bike.
I should note that, when we were in San Francisco, we had a lot of people who were very committed to living in the city and only working where they could bike / walk / train to. We lost all of these people when we moved to Menlo Park. The only bike/train people who we kept were the company founders, who sucked it up and started driving once we could no longer fit in the offices near the train stations.
Though everyone in the Bay Area needs (access to) a car, driving in the Bay Area is No Fun.
There's stop and stop traffic on every major highway. Parking in San Francisco is very expensive and hard to find.
You need to be flexible to get around the Bay Area, willing to try different solutions.