I'll Call Before I Come Over

People here  such as friends, repairmen, clients, etc. who need to come to my house always tell me, "I'll call before I come by."  

But you know what, they always just show up.  

For example, last week, I was busy in the shower and my cell phone rang.  The person didn't leave a message, so I didn't make much of it and thought it must not have been important.  Well, a few days later I found out it was someone I did an editing job for and he called from my FRONT GATE with flowers as a thank you.  Result, I suppose his wife got the flowers instead.  No harm done, I suppose.  But, the point is, does "call before you come" mean to you "call as you walk up to the door"?  Generally, I think not.

Then again today I talked to a repairman and he took down my number and said he'd call before he came by.  Well, low and behold but at 5PM there's someone ringing my bell and it's one of the repairman's workers.  No call.  

It's all very interesting to me.  To me, these people are just inconveniencing themselves by apparently assuming that I am home literally all the time (ok, I really am home nearly all the time since I have no job, but that's beside the point).  I don't get it....