why do I expect to see a lot of self driving autonomous cars and trucks and buses set on fire around the world over time?

Because the primary job of men on earth is driving vehicles whether they are cars or trucks of various kinds or buses. When you make all these vehicles or even some of them self driving you take away the livelihood of these men.

So, it is logical to me that you are going to see thousands of these vehicles set on fire by men who have lost their driving jobs to Autonomous driving vehicles that don't need a driver whether they are cars or trucks or buses around the world. 

Note: Also when you set on fire something like this with lithium Ion Batteries you might not be able to fully put out these flames for over a month because of the true nature of these batteries once they reach a certain temperature. Also, they can explode like you just saw in videos and spew dangerous flames and chemicals and pieces of themselves all over people setting their clothes on fire too.

So, setting these things on fire is incredibly toxic and can also have the effect in some ways of a hand grenade going off so you need to be at least 100 feet away from one of these when they are on fire so you aren't killed or injured or your lungs destroyed breathing dangerous gases coming off these fires for about 1 month or more even if doused with water. Water doesn't permanently put out fires like this either. 

Note: I look at Autonomous self driving cars on fire a lot like how I feel about Transformers exploding on telephone poles. In other words you don't want to be around them on fire or you could die or be sent to the hospital.

So, if you see or hear a transformer exploding during a storm be sure you are protected by a house or wall or building when this happens or you could die. The same with an autonomous Car on fire. Stay way back and don't breathe any vapors coming off this so be sure you are upwind from a burning autonomous car or truck or bus because being downwind can maim or kill you.