It took me several days to get an unlock code from T-Mobile, for a phone I'd paid for unsubsidized. And, they make a big deal out of the process, and make a lot of noise about possibly being unable to provide unlock codes if they don't have them.
That's not to say T-Mobile isn't better than some other carriers. As I understand it, they are. But, I shouldn't have to ask permission to use my phone, that I paid $600 for, in Mexico for a few weeks, while I continue to pay for my US service.
Making unlocking a phone yourself illegal is anti-consumer and pro-corporate in ways that I find extremely distasteful and it makes me angry that the US state serves corporate interests so much more enthusiastically than individual interests.