Well to be fair even if Android were completely open: In the US, your phone is still beholden to small number carriers. They get to decide what devices can connect to their network. This determines much of the hardware and software of the phones on their networks.

So ultimately they own the devices that connect to them. That's why I've already stopped paying for phones and just get free ones when offered. If I do pay for one again it'll just be the cheapest Chinese one available.