>How come I can do what I want with my computer, but not my phone?

It kind of started because phones interact with phone networks and the network companies didn't want hacked software mucking up their networks. I realise the baseband part is separate from the rest of the phone but it's always been that way with every cell phone I've had over 30 years, that they are part locked down.

Whereas none of the regular computers and laptops have been especially locked down.

It would be cool if you could just connect your laptop to a radio and connect to cell networks but I don't think any of them allow that?