Why we don't have sub-stocks

Be able to invest in the parts of the company that appeal to you the most. For example, suppose I am most interested in Tesla's artificial intelligence technology compared to Tesla's EV car business. The market should give me the option to buy Tesla’s various sub-stocks-Tesla Motors-Tesla Artificial Intelligence-Tesla Semiconductors-Tesla Logistics and Supply Chain-Tesla Solar-Tesla Finance and Insurance

It may hinder vertical integration, but it will encourage resource availability/unavailability in sub-business units. For example, I think Wells Fargo is a good bank, but I hate that they continue to focus on expanding physical bank branches-investors can start shorting WF branches and stop wasteful investments in ineffective models.