What is with the time window?

I think I mentioned before that I moved..... : ) And now, I am having the locks changed. When I called to set up the appointment with the locksmith (of course, the only one my building does business with), he was very nice and we set a day. Then he proceeds to tell me that I have a 9 AM to 5 PM window. At first, I wasn't paying great attention so I didn't notice, and then suddenly I was like, what did he just say? So I asked him to say it again. Sure enough, he was telling me (with a straight face, I am assuming) that the technician would be here ANY TIME in that time frame. I was like, "are you serious"? and he was like, "oh, he'll give you a call when he's like twenty minutes away". Like that was the silver key of consolation that would make the entire scenario make sense. Oh, he'll give me twenty minutes huh? How helpful and accomodating of him. So, I was like, "Let me get this straight, you expect me to stay within 20 minutes of my house for the ENTIRE business day of Tuesday?" and the guy seemed a little surprised that it was a problem. Granted, I am currently unemployed, but how do fully functioning members of society who have a 9-5 manage to get anything done around here? I mean, I am almost lucky I haven't found a job yet because that means I can actually take care of crap like this. And SO many people do this bull sh*t time frame stuff. I don't understand. I get that some appointments may take longer than others, so find out what you are going to be doing and plan accordingly. In this day and age with all of the scheduling software and technology, there should be no time frame. In fact, we should be moving in the other direction. Someone should be able to say, "we will have a technician at your house at 9:12 AM Tuesday morning. There should be some high tech scheduling going on. Instead, it seems to be worsening. At the rate we're going, the next time you need a plumber they're going to say, "It could be anytime in the month of May. We'll let you know when we're on our way."