nope, not a friend, don't even know the person.  But I have to say I side with the home owner.  If the dog walker was putting his bag of dog poop in a full can that was out to be picked up, I'd agree with you.  In this case, the dog walker is putting it in an empty trash can it it will sit in the can all week.  not such a problem in the cold weather, but in the summer heat, stinking up the can.  I think it's very inconsiderate of the dog walker.  take it home and put it in your own trash or in a public trash can.  I do!
 

The homeowner should approach the dog walker and ask her NOT to put her dogs' poop in her can...

I don't think the home owner sees who it is because they leave for work before the garbage is picked up.  but they have installed a camera or put up a sign...not sure what they decided to do.

my dog can make the biggest poop of his life in my yard but as soon as his leash is on and he steps off the property he musters up at least one more on someone else's yard.  I pick it up and take it home.  not difficult!  it's one of the joys of dog ownership!  LOL