The thing is, phones are unlocked by default when they're manufactured. The very first phones to hit the streets are the unlocked versions, because they're the "plain vanilla" model.

As I have mentioned before in other threads, here in Finland locking was actually illegal for many years, so for many years everyone used unlocked phones, and it didn't cause any problems at all.

Operators which lock phones deliberately lock them to stop you changing operator, there's absolutely no technical reason for locking.

All that locking does is reduce competition between operators, which raises prices and lowers service quality. It makes them try less hard to please their customers.