Do locksmiths change locks?

[Scott Townsend]

I had a tenant leave me a voicemail saying he locked himself out of my condo. By the time I called him back he had scheduled a locksmith to come let him in. So the good news was that it saved me the trip and it was on the tenant's dime, but my question is how often can locksmiths open doors without damaging/replacing the lock? Appreciate any help!