Also, it's would pretty naive to think that governments would allow a single company to have such sort of monopoly like you describe.
The idea is that gathering this data may be a prerequisite to resolving the bajillions fringe-cases that are currently in the way of level 4 autonomy.
With all Toyota's data, you will have to buy a brand new car to get whatever improvements your data contributed to the system.
With Tesla, you get those improvements while you're asleep and maybe your car drives a bit better. For a tech-centric space where people are used to software improving overtime, Tesla will have an edge.
If amount of data collected and OTA are Tesla's big edge then there's even less chance they will dominate the market and put all their competitors out of business, because those advantages are going to go away over the next couple of years.