When you are locked out, a locksmith should ask you for your credentials everytime with no exception. This is to ensure that you, and the Locksmith are legally able to enter the premises. You would not want anyone to enter you home without proper authority, so do not accept any locksmith who does not ask for this. If they do not, you should report them to either the Master Locksmiths association,Locksmiths Guild or the Police.
A person locked out searched Locksmith Paddington in Google and found me. After me questioning and asking for proof of residency, the person finally admitted they were the Landlord and just wanted to enter for some obscure reason, which of course is illegal.