In general the high end "flagship" devices have unlockable bootloaders, but the devices that the vast majority of people can afford do not. I expect to see a similar thing in laptops. If you can throw down 2-3,000 USD on a new XPS or Thinkpad X1C you'll likely get the privilege of an unlockable bootloader. For most of the non-US world that's a huge chunk of everyone (including developers) salaries.
In general the high end "flagship" devices have unlockable bootloaders, but the devices that the vast majority of people can afford do not. I expect to see a similar thing in laptops. If you can throw down 2-3,000 USD on a new XPS or Thinkpad X1C you'll likely get the privilege of an unlockable bootloader. For most of the non-US world that's a huge chunk of everyone (including developers) salaries.