Its actually illegal to lock ecu's/ecm/pcm if the customer has paid for the tune, because he has paid for the said license and now owns the tune. This has been tried in court and I encourage locked victims to pursue this....
Many tuners still lock tunes, but most reasonable tuners arent interested what the locked tune is, and would rather start from fresh anyway, because heaven only knows what the last tuner stuffed up....
Tuners that lock, hide under the pretense that they dont want other to know/learn from their knowledge, but in my opinion, they hide their lack of knowledge, and their dodgy tune.