1. Monopolies are a thing and the first few to the market with self driving systems will be ubiquitous. You can't avoid it. Waymo/Google will license their solution to car manufacturers, who will be stuck with it because it's going to be very expensive to get their own self driving certified in all their target markets.
2. Yes, let's limit everyone to either walking/cycling, public transit, or megacorporation control over their freedom of movement. There's certainly not a western government currently rounding up dissidents that would just tell their beloved corporations to drive people with certain backgrounds to Alligator Alcatraz.
3. Yes, but why are we giving them even more control over our lives voluntarily? Especially since we're talking about something that can literally lock its doors and drive you to somewhere you didn't want to go.

I've never been much of a conspiracy nut, but this is where I agree with them. I don't want government and corporations to say when and where I can go. Walking is an option for me 90% of the time, and one I take very often, but what if I literally need to fucking escape an invasion? Considering it's happening right now, 4 countries south of me, and said invader has demonstrated that they love taking down communications networks, what the fuck options am I going to have left if I need to drive 1000 km in a day and my car's like "No Internet connection, I'm staying put"? If you're in the US you don't have THAT risk, but you still have the whole issue of a dictator being able to decide where you're driving. Public transit is great, but it's not ready for mass surges of people fleeing and if someone's after you personally, it creates choke points (stations) where it's easy to grab you. I'm not saying cars are super hard to track, but when there are a lot of targets, everyone being spread out means it's harder to get a lot of people at once.